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