#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 arr[N];
    char *ptr = arr;
    for (int i = 0; i < N; i++) {
        scanf(" %c", (ptr + i));
        if(!isalpha(*(ptr + i))) {
            printf("Invalid input");
            return 0;
        }
    }
    int sumEven = 0;, sumOdd = 0;
    for (int i = 0; i < N; i++) {
        int ascii = *(ptr + i);
        if(ascii % 2 == 0)
           sumEven += ascii;
        else
           sumOdd += ascii;
    }
    int diff = abs(sumEven -  sumOdd);
    printf("%d", diff);
    return 0;
}