#include <iostream>
#include "math.h"
#include <string>
using namespace std;
int main() {
	string N;
	int count0 = 8;
	int count = 0;
	cin >> N;
	for (int i = 0; i < N.size(); i++) {
		if (N[i] == '0') {
			count++;
		}
	}
	if (count <= count0)cout << count0 - count << endl;
	else if (count > count0)cout << count - count0 << endl;
	return 0;
}