#include <iostream>
#include <string>
using namespace std;
inline int decode(char c)
{
if(c >= '0' and c <= '9'){
return c-'0';
} else {
return 0;
}
}

int main()
{
string s;
cin >> s;
int num = 0;
for(const char c:s){
num += decode(c);
}
cout << num << endl;
return 0;
}