#include <stdio.h>
#include <ctype.h>
#include <stdio.h>
int main() {
    int N;
    scanf("%d", &N);
    if (N <= 0)
    {
        printf("Invalid input");
        return 0;
    }
    char arr[200];
    char *ptr = arr;
    for (int i = 0; i < N; i++)
    {
        scanf(" %c", ptr + i);
        if (!isalpha(*(ptr + i)))
        {
            printf("Invalid input");
            return 0;
        }
    }
    int evensum = 0,oddsum = 0;
    for (int i = 0; i < N; i++)
    {
        int ascii = *(ptr + i);
        if (ascii % 2 == 0)
        evensum += ascii;
        else
        oddsum += ascii;
    }
    int diff = abs(evensum - oddsum);
    printf("%d", diff);
    return 0;
}