#include <stdio.h>

int zero(char *vc) {
	int counter, i;

	while(vc[i] != '\0') {
		if(vc[i] == '0')
			counter++;
		i++;
	}
	return (counter);
}

int sa(int a, int b){
	return (a >= b ? a - b : b - a );
}

int main(void){
	char nyu[17];
	int i;
	scanf("%s", nyu);
	printf("%d\n", sa(zero(nyu), 8));

	return 0;
}