#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;
}