var photo=new Array()
var num=0
photo[0]="pm1.jpg"
photo[1]="pm2.jpg"
photo[2]="pm3.jpg"
photo[3]="pm4.jpg"
photo[4]="pm5.jpg"
photo[5]="pm6.jpg"
photo[6]="pm7.jpg"
photo[7]="pm8.jpg"
photo[8]="pm9.jpg"
photo[9]="pm10.jpg"
photo[10]="pm11.jpg"
photo[11]="pm12.jpg"
photo[12]="pm13.jpg"
photo[13]="pm14.jpg"
photo[14]="pm15.jpg"
photo[15]="pm16.jpg"
photo[16]="pm17.jpg"
numero=num+1

function precedente() {
  if (num>0) {
    num--
      document.image.src=photo[num];
    numero=num+1
  }
}
function suivante() {
  if(num<photo.length-1) {
    num++
      document.image.src=photo[num];
    numero=num+1
  }
}