#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);
        int(ascii % 2 == 0)
        {
            evensum += ascii;
        }
        else{
            oddsum += ascii;
        }
    }
    printf("%d\n", abs(evensum - oddsum));
    return 0;
}