let a = [1, 2, 3, 4, 5, 6];
var left = 0, right = 5;
var found = false;
var target = 5;
while(left <= right) {
   var mid = Math.floor((left + right) / 2);
   if(a[mid] == target) {
       found = true;
       break;
   }
   else if(a[mid] < target) {
       left = mid + 1;
   }
   else {
       right = mid - 1;
   }
}
if(found) {
   print("YES");
}
else {
   print("NO");
}