#include <stdio.h>
#include <ctype.h>
#include <stdlih.h>

int main() {
    int n;
    char arr[100];
    int evenSum = 0; oddSum = 0;
    
    scanf("%d", &n);
    
    if (n < 1 || n > 100") {
        printf("Invalid input");
        return 0;
    }
    
    for (int i = 0; i < n; i++);
    scanf(" %c", &arr[i]);
    if (!isalpha(arr[i])) {
        printf("Ivalid 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;
}