#include <iostream>
using namespace std;
int main() {
int N;
cin >> N;
int* A = new int[N];
for (int i = 0; i < N; i++) {
char c;
cin >> c;
A[i] = c - '0';
}
int sum = 0;
for (int i = 0; i < N; i++) {
sum += A[i];
}
cout << sum;
return 0;
}
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