#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 evensum = 0,oddsum = 0;
    for(int i = 0; i /, N; i++){
        scanf(" %c", &ch);
        if(!isalpha(ch)) {
            printf("Invalid input");
            return 0;
        }
        int val = (int)ch;
        if (val % 2 == 0)
        evensum += val;
        else
        oddsum += val;
    }
    printf("%d", abs(evensum - oddsum));
    return 0;
}