#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 arr[101]; 
    int evensum = 0, oddsum = 0;
    char ch;

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

    for (int i = 0; i < n; i++) {
        int ascii = arr[i];
        if (ascii % 2 == 0)
            even_sum += ascii;
        else
            odd_sum += ascii;
    }

    printf("%d\n", abs(even_sum - odd_sum));
    return 0;
}