#include<stdio.h>
#include<ctype.h>
#include<stdlib.h>

int main() {
    int n;
    scanf("%d",&N);
     if (n<=0) {
         printf("Invalid input");
         return 0;
     }
     char ch;
     int sumEven=0,sumOdd =0;
     for(int i=0 ; i<n;i++){
         scanf("%c",&ch);
         if(!isalpha(ch)){
             printf("Invalid input");
             return 0;
         }
    char*ptr=&ch;
    int ascii=(int)(*ptr);
    if(ascii%2==0)
    sumEven+=ascii;
    else
    sumOdd+=ascii;
     }
     int diff=abs(sumEven-sumOdd);
     printf("%d",diff);
     return 0;
}