// editor1
#include<stdio.h>
#include<stdlib.h>
#include<ctype.h>
#include<string.h>
int main(){
    int n;
    scanf("%d", &n);
    if(n < 1 || n > 100) {
        printf("Invalid input");
        return 0;
    }
    char initials [101];
    int even_sum = 0; odd_sum = 0;
    for(int i = 0; i < n; i++){
        scanf(" %c", &initials[i]);
        if(!isalpha(initials[i])){
            printf("Invalid input\n");
            return 0;
        }
        char * ptr = &initials[i];
        int ascii_val = (int)(*ptr);
        if(ascii_val %2 == 0)
        even_sum += ascii_val;
        else
        odd_sum += ascii_val;
    }
    int result = abs(even_sum - odd_sum);
    printf("%d\n", result);
    return 0;
}