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

int main() 
{
    int n;
    scanf("%d", &n);
    if (n <= 0) 
    {
        printf("Invalid input\n");
        return 0;
    }
    char b[101];
    int even = 0, odd = 0;
    for (int i = 0; i < n; i++) 
    {
        scanf(" %c", &b[i]);
        if (!isalpha(b[i])) 
        {
            printf("Invalid input\n");
            return 0;
        }
    }
    char *ptr = b;
    for (int i = 0; i < n; i++, ptr++) 
    {
        int c = (int)(*ptr);
        if (c % 2 == 0)
            even += c;
        else
            odd += c;
    }
    int d = abs(even - odd);
    printf("%d\n", d);
    return 0;
}