include <bits/stdc++.h>

using namespace std;

int main() {

unsigned long long n=0,num=0;
cin >>n;
num=n;
int i=0;
for(;num!=0;i++){
	num/=10;
}
//cout << i;
unsigned sum=0;
for(;i>=1;i--){
	sum += int(n / pow(10,i)) % 10;
}
sum += n % 10;
cout << sum;
return 0;

}