int a[10];
int x = 0;
int k = 0;

while (k < 10) {
  read(x);
  a[k] = x;
  k = k + 1;
}
x = a[9];

/* Look for the first occurrence of the last element */
k = 0;
while (1) {
  /* Not actually an infinite loop:
     we cannot go beyond the last element */
  if (x == a[k]) {
    write(k);
    return;
  }
  k = k + 1;
}