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

int main () {
    int n;
    char arr[100];
    int evenSum = 0, oddSum = 0;
    
    scanf("%d", &n);
    
    if (n < 1 || n > 100) {
        printf("Invalid input\n");
        return 0;
    }
    
    for (int i = 0; i < n; i++) {
        scanf(" %c",&arr[i]);
        if (!isalpha(arr[i])) {
            printf("Invalid input\n");
            return 0;
        }
    }
    
    char *ptr = arr;
    
    for (int i = 0; i < n; i++) {
        int ascii = (int)*(ptr + 1)
        if (ascii % 2 == 0)
            evenSum += ascii;
            else
               oddSum += ascii;
    }
    
     printf("%d\n", abs(evenSum - oddSum));
     
     return 0;
}