#include <iostream>
#include <string.h>
using namespace std;
int main() {
char str[100000];
cin >> str;
int len = strlen(str);
long long int sum=0;
for(int i=0;i<len;i++){
sum+=(str[i]-'0');
}
cout << sum;
return 0;
}
I2luY2x1ZGUgPGlvc3RyZWFtPgojaW5jbHVkZSA8c3RyaW5nLmg+CnVzaW5nIG5hbWVzcGFjZSBzdGQ7CgppbnQgbWFpbigpIHsKCWNoYXIgc3RyWzEwMDAwMF07CgljaW4gPj4gc3RyOwoJaW50IGxlbiA9IHN0cmxlbihzdHIpOwoJbG9uZyBsb25nIGludCBzdW09MDsKCWZvcihpbnQgaT0wO2k8bGVuO2krKyl7CgkJc3VtKz0oc3RyW2ldLScwJyk7Cgl9Cgljb3V0IDw8IHN1bTsKCXJldHVybiAwOwp9