if (document.images) {
  var boton1_off = new Image();
  boton1_off.src = "images/e1.png";
  var boton1_on = new Image();
  boton1_on.src = "images/boton_evento_2010.png";
  
   var boton2_off = new Image();
  boton2_off.src = "images/e2.png";
  var boton2_on = new Image();
  boton2_on.src = "images/boton_evento_2010.png";
  
   var boton3_off = new Image();
  boton3_off.src = "images/e3.png";
  var boton3_on = new Image();
  boton3_on.src = "images/boton_evento_2010.png";
  
   var boton4_off = new Image();
  boton4_off.src = "images/e4.png";
  var boton4_on = new Image();
  boton4_on.src = "images/boton_evento_2010.png";
  
   
   var boton5_off = new Image();
  boton5_off.src = "images/e5.png";
  var boton5_on = new Image();
  boton5_on.src = "images/boton_evento_2010.png";
  
  var boton6_off = new Image();
  boton6_off.src = "images/o1.png";
  var boton6_on = new Image();
  boton6_on.src = "images/boton_obra.png";
  
   var boton7_off = new Image();
  boton7_off.src = "images/o2.png";
  var boton7_on = new Image();
  boton7_on.src = "images/boton_obra.png";
  
   var boton8_off = new Image();
  boton8_off.src = "images/o3.png";
  var boton8_on = new Image();
  boton8_on.src = "images/boton_obra.png";
  
   var boton9_off = new Image();
  boton9_off.src = "images/o4.png";
  var boton9_on = new Image();
  boton9_on.src = "images/boton_obra.png";
  
   
   var boton10_off = new Image();
  boton10_off.src = "images/o5.png";
  var boton10_on = new Image();
  boton10_on.src = "images/boton_obra.png";
}

var boton11_off = new Image();
    boton11_off.src = "images/c1.png";
  var boton11_on = new Image();
  boton11_on.src = "images/boton_circulo.png";
  
   var boton12_off = new Image();
  boton12_off.src = "images/c2.png";
  var boton12_on = new Image();
  boton12_on.src = "images/boton_circulo.png";
  
   var boton13_off = new Image();
  boton13_off.src = "images/c3.png";
  var boton13_on = new Image();
  boton13_on.src = "images/boton_circulo.png";
  
   var boton14_off = new Image();
  boton14_off.src = "images/c4.png";
  var boton14_on = new Image();
  boton14_on.src = "images/boton_circulo.png";
  
   
   var boton15_off = new Image();
  boton15_off.src = "images/c5.png";
  var boton15_on = new Image();
  boton15_on.src = "images/boton_circulo.png";

  var boton16_off = new Image();
  boton16_off.src = "images/z1.png";
  var boton16_on = new Image();
  boton16_on.src = "images/boton_colegio.png";
  
   var boton17_off = new Image();
  boton17_off.src = "images/z2.png";
  var boton17_on = new Image();
  boton17_on.src = "images/boton_colegio.png";
  
   var boton18_off = new Image();
  boton18_off.src = "images/z3.png";
  var boton18_on = new Image();
  boton18_on.src = "images/boton_colegio.png";
  
   var boton19_off = new Image();
  boton19_off.src = "images/z4.png";
  var boton19_on = new Image();
  boton19_on.src = "images/boton_colegio.png";
  
   
   var boton20_off = new Image();
  boton20_off.src = "images/z5.png";
  var boton20_on = new Image();
  boton20_on.src = "images/boton_colegio.png";

// Carga de imagen cuando el ratón pasa por encima
function entra(boton) {
  if (document.images) {
    if (boton == 'boton1') {
      document.images[boton].src = boton1_on.src;
    }
    if (boton == 'boton2') {
      document.images[boton].src = boton2_on.src;
    }
    if (boton == 'boton3') {
      document.images[boton].src = boton3_on.src;
    }
    if (boton == 'boton4') {
      document.images[boton].src = boton4_on.src;
    }
    if (boton == 'boton5') {
      document.images[boton].src = boton5_on.src;
    }
      if (boton == 'boton6') {
      document.images[boton].src = boton6_on.src;
    }
    if (boton == 'boton7') {
      document.images[boton].src = boton7_on.src;
    }
    if (boton == 'boton8') {
      document.images[boton].src = boton8_on.src;
    }
    if (boton == 'boton9') {
      document.images[boton].src = boton9_on.src;
    }
    if (boton == 'boton10') {
      document.images[boton].src = boton10_on.src;
    }
      if (boton == 'boton11') {
      document.images[boton].src = boton11_on.src;
    }
      if (boton == 'boton12') {
      document.images[boton].src = boton12_on.src;
    }
      if (boton == 'boton13') {
      document.images[boton].src = boton13_on.src;
    }
      if (boton == 'boton14') {
      document.images[boton].src = boton14_on.src;
    }
      if (boton == 'boton15') {
      document.images[boton].src = boton15_on.src;
    }
          if (boton == 'boton16') {
      document.images[boton].src = boton16_on.src;
    }
          if (boton == 'boton17') {
      document.images[boton].src = boton17_on.src;
    }
          if (boton == 'boton18') {
      document.images[boton].src = boton18_on.src;
    }
          if (boton == 'boton19') {
      document.images[boton].src = boton19_on.src;
    }
          if (boton == 'boton20') {
      document.images[boton].src = boton20_on.src;
    }
    
  }
}

// Carga de imagen cuando el ratón abandona el área de la imagen
function sale(boton) {
  if (document.images) {
    if (boton == 'boton1') {
      document.images[boton].src = boton1_off.src;
    }
    
    if (boton == 'boton2') {
      document.images[boton].src = boton2_off.src;
    }
    if (boton == 'boton3') {
      document.images[boton].src = boton3_off.src;
    }
    if (boton == 'boton4') {
      document.images[boton].src = boton4_off.src;
    }
    if (boton == 'boton5') {
      document.images[boton].src = boton5_off.src;
    }
    
     if (boton == 'boton6') {
      document.images[boton].src = boton6_off.src;
    }
    
     if (boton == 'boton7') {
      document.images[boton].src = boton7_off.src;
    }
     if (boton == 'boton8') {
      document.images[boton].src = boton8_off.src;
          }
     if (boton == 'boton9') {
      document.images[boton].src = boton9_off.src;
    }    
      if (boton == 'boton10') {
      document.images[boton].src = boton10_off.src;
    }     
      if (boton == 'boton11') {
      document.images[boton].src = boton11_off.src;
    }
      if (boton == 'boton12') {
      document.images[boton].src = boton12_off.src;
    }
      if (boton == 'boton13') {
      document.images[boton].src = boton13_off.src;
    }
      if (boton == 'boton14') {
      document.images[boton].src = boton14_off.src;
    }
      if (boton == 'boton15') {
      document.images[boton].src = boton15_off.src;
    }
     if (boton == 'boton16') {
      document.images[boton].src = boton16_off.src;
    }
     if (boton == 'boton17') {
      document.images[boton].src = boton17_off.src;
    }
     if (boton == 'boton18') {
      document.images[boton].src = boton18_off.src;
    }
     if (boton == 'boton19') {
      document.images[boton].src = boton19_off.src;
    }
     if (boton == 'boton20') {
      document.images[boton].src = boton20_off.src;
    }
    
    
    
    
    
    
  }
}