// sum of first and last digit
// writen by : sammo
#include <stdio.h>
int main()
{
    int a;
    scanf("%d",&a);
    int n = a%10;
    while(a != 0){
      a/=10;
      if(a < 10){
        break;
      }
    } 
    printf("%d",a+n);
    
    return 0;
}