#include <bits/stdc++.h>
using namespace std;

int main()
{
	string S;
	cin >> S;

	int ans = 0;
	for( int i = 0; i < S.size(); i++ ) {
		if( S[i] == '0' ) ans++;
	}
	ans = abs( ans - 8 );

	cout << ans << endl;
}