#include<stdio.h>
#include<ctype.h>
#include<stdlib.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++){
        intascii=(int)*(ptr + i);
        if(ascii%2==0)
        evensum+=ascii;
        else
        oddsum+=ascii;
    }
    printf("%d\n",abs(evensum-oddsum));
    re
}