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

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

    if (n <= 0) {   
        printf("Invalid Input\n");
        return 0;
    }

    char ch;
    int evenSum = 0, oddSum = 0;

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

        int asciiVal = (int)ch;
        if (asciiVal % 2 == 0)
            evenSum += asciiVal;
        else
        ddSum += asciiVal;
    }

    printf("%d\n", abs(evenSum - oddSum));
    return 0;
}