#include<iostream>
using namespace std;
int main(void) {
int n;
cin >> n;
char ch;
int sum = 0;
for (int i = 0; i<n; i++) {
cin >> ch;
sum += (ch - '0');
}
cout << sum;
return 0;
}
I2luY2x1ZGU8aW9zdHJlYW0+CnVzaW5nIG5hbWVzcGFjZSBzdGQ7CgppbnQgbWFpbih2b2lkKSB7CglpbnQgbjsKCWNpbiA+PiBuOwoJY2hhciBjaDsKCWludCBzdW0gPSAwOwoJZm9yIChpbnQgaSA9IDA7IGk8bjsgaSsrKSB7CgkJY2luID4+IGNoOwoJCXN1bSArPSAoY2ggLSAnMCcpOwoJfQoKCWNvdXQgPDwgc3VtOwoJcmV0dXJuIDA7Cn0=