#include <iostream.h>

void main()
{
	int vals[101];
	int n;

	cin >> n;
	while (n != 0) {
		for(int i=0; i<n; i++) {
			cin >> vals[n-i];
		}
		int j=n-1;
		while (j > 0) {
			if (vals[j+1]-1 < vals[j])
				vals[j] = vals[j+1]-1;
			if (vals[j] == 0)
				break;
			j--;
		}
		cout << j << endl;

		cin >> n;
	}
}