#include <iostream>
#include <string>
#include <string.h>
#include <vector>
#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <iomanip>
#include <climits>
#define ll long long
using namespace std;
int main() {
int n;
cin >>n;
string digits;
cin>>digits;
int sum =0;
for(char digit: digits){
sum += digit-'0';
}
cout<<sum<<endl;
return 0;
}
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