#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 even_sum = 0, odd_sum = 0;
    for(int i = 0; i < N; i++){
        scanf(" %c", &ch);
        if(!isalpha(ch)){
            printf("Invalid Input");
            return 0;
        }
        int ascii_val = (int)ch;
        if(ascii_val % 2 == 0){
            even_sum += ascii_val;
        }
        else{
            odd_sum += ascii_val;
        }
    }
    int result = abs(even_sum - odd_sum);
    printf("%d", result);
    return 0;
}