代码
#include<bits/stdc++.h>
using namespace std;
string s;
int ans = 0;
int main() {
// freopen("number.in", "r", stdin);
// freopen("number.out", "w", stdout);getline(cin, s);for (int i = 0; i < s.size(); i++)if (s[i] == '1') ans++;printf("%d", ans);return 0;
}