#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
int main() {
    int n, i, evenSum = 0, oddSum = 0;
    char ch;
    scanf("%d", &n);
    if (n <= 0|| n > 100) {
        printf("Invalid input");
        return 0;
    }
    for(1 = 0; i < n; i++) {
        scanf(" %c", &ch);
        if (!isalpha(ch)) {
            printf("Invalid input");
            return 0;
        }
        if ((int)ch % 2 == 0)
        evenSum += (int)ch;
        else
           oddSum += (int)ch;
    }
    printf("%d", abs(evenSum - oddSum));
    return 0;
}