#include <iostream>
#include <string>
#include <ctype.h>
using namespace std;

int main(){
	string S;
	cin >> S;
	int sum = 0;
	for(size_t i = 0; i < S.size(); i++){
		if(isdigit(S[i])) sum += S[i] - '0';
	}
	cout << sum << endl;
	return 0;
}