// yukicoder: No.671 1000000007
// 2019.4.14 bal4u

#include <stdio.h>

#define ABS(a) ((a)>=0?(a):-(a))
char N[20], *p = N+1;

int main(void)
{
	int n;
	scanf("%s", N);
	n = 0; while (*p == '0') n++, p++;
	printf("%d\n", ABS(n - 8));
	return 0;
}