#include <bits/stdc++.h>
using namespace std;

int main( int argc, char *argv[] )
{
int i;
int iSum;
char S[ 200 ];
char C;

	ios::sync_with_stdio( false );
	cin.tie( 0 );

	cin >> S;

	i = 0;
	iSum = 0;
	C = S[ i ];
	while( C >= '0' && C <= '9' )
	{
		i++;
		iSum += ( C - '0' );
		C = S[ i ];
	}

	cout << iSum << endl;

	return 0;
}