/*******************************************************
 * cattle_train -- yukicoder うし数列
 * 2019/07/7 kamato02
*******************************************************/

#include<stdio.h>
char cattle_train[103];
int main() {

	int i;
	int count = 0;

	scanf("%s",cattle_train);

	if(cattle_train[0] != '1') {
		printf("-1");
		return (0);
	}

	for(i = 1;cattle_train[i] != '\0';i++) {
		if(cattle_train[i] == '3') {
			count++;
		} else {
			printf("-1");
			return (0);
		}
	}

	printf("%d",count);
	return (0);
}