#include <stdio.h>

int min(int x, int y)
{
  return (x < y) ? x : y;
}

int main(void)
{
  int n, ring, i, prev, ans, p;

  while (scanf("%d", &n) == 1 && n) {
    prev = n+1;
    ans = 0;
    for (i = 0; i < n; i++) {
      scanf("%d", &ring);
      p = min(prev-1, ring);
      if (p <= 0) {
	ans++;
      }
      prev = p;
    }
    printf("%d\n", ans);
  }
  return 0;
}