#include<stdio.h>
#include<ctype.h>
#include<stdio.h>
int main(){
    int N;
    scanf("%d",&N);
    if(N < 0){
        printf("Invalid Input");
        return 0;
    }
    char arr[100];
    for(int i = 0;i < N; i++){
        scanf(" %c",&arr[i]);
    }
    int evenSum = 0, oddSum = 0;
    char*ptr = arr;
    for (int i = 0; i < N; i++){
        if(!isalpha(*(ptr + i))){
            return 0;
        }
        int ascii =*(ptr + i);
        if(ascii % 2 == 0)
        evenSum += ascii;
        else
        oddSum += ascii;
    }
    printf(" %d", abs(evenSum - oddSum));
    return 0;
}