#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 ch;
    int even_sum = 0, odd_sum = 0;

    for (int i = 0; i < n; i++) {
        scanf(" %c", &ch); 
        if (!isalpha(ch)) {
            printf("Invalid input\n");
            return 0;
        }
        int ascii_val = (int)ch;
        if (ascii_val % 2 == 0)
            even_sum += ascii_val;
        else
            odd_sum += ascii_val;
    }
    printf("%d\n", abs(even_sum - odd_sum));
    return 0;
}