#include<stdio.h>

int main(void){
    
    int N;
    scanf("%d",&N);
    
    int sum=0;
    
    for(int i=0;i<9;i++){
        if(N%10==0)sum = sum+10;
        else sum = sum + N%10;
        N = N/10;   }
    
    printf("%d\n",sum);
    
    return 0;
}