#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 (!isalphe(arr[i])) {
        printf("Invalid input\n");
        return 0;
    }
}
    char *ptr = arr;
    for (int i = 0; i < n; i++) {
        int ascii = (int)*(ptr + i);
           if (asii % 2 == 0)
           evenSum += ascii;
           else
              oddSum += ascii;
    }
    printf("%d\n", abs(evenSum - oddSum));
    return 0;
    }