#include<stdio.h>
#include<ctype.h>
#include<stdli.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);
        if (ascii % 2 == 0)
           evensum += ascii;
        else
            oddsum += ascii;
    }
    
    printf("%d\n",abs(evensum - oddSum));
    
    return 0;
}