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

int main() {
    int n;
    scanf("%d", &n);

    if (n < 0 || n > 100) {
        printf("Invalid input\n");
        return 0;
    }

    char initials[n];
    for (int i = 0; i < n; i++) {
        scanf(" %c", &initials[i]); 
        if (!isalpha(initials[i])) {
            printf("Invalid input\n");
            return 0;
        }
    }

    int even_sum = 0, odd_sum = 0;
    char *ptr = initials;

    for (int i = 0; i < n; i++) {
        int ascii_val = *(ptr + i);
        if (ascii_val % 2 == 0)
            even_sum += ascii_val;
        else
            odd_sum += ascii_val;
    }

    printf("%d\n", abs(even_sum - odd_sum));

    return 0;
}