#include <iostream>
using namespace std;
long long number , sum = 0;
int main() {
cin >> number;
while (number) {
sum += number % 10;
number /= 10;
}
cout << sum << endl;
return 0;
}

#include <iostream>
using namespace std;
long long number , sum = 0;
int main() {
cin >> number;
while (number) {
sum += number % 10;
number /= 10;
}
cout << sum << endl;
return 0;
}