// editor1
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
int main()
{
    int N; 
    scanf("%d", &N);
    if (N <= 0)
    {
        printf("Invalid input");
        return 0;
    }
    char ch;
    int even_sum = 0, odd_ sum= 0;
    for (int i = 0; i < N; i++)
    {
        scanf("%c", &ch);
        if (!isalpha(ch))
        {
            printf("Invalid input");
            return 0;
        }
        int ascii = (int)ch;
        if (ascii % 2 == 0)
        even_sum += ascii;
        else
        odd_sum += ascii;
    }
    int result = abs(even_sum - odd_sum);
    printf("%d", result);
    return 0;
}