#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 ch;
    int evenSum=0,oddSum=0;
    for(int i=0;i<N;i++)
    {
        scanf(" %c",&ch);
        if(!isalpha(ch))
        {
            printf("Invalid input");
            return 0;
        }
        int ascii=(int)ch;
        if(ascii%2==0)
        {
            evenSumascii;
        }
        else
        {
            oddSum+=ascii;
        }
    }
    int result=abs(evenSum-oddSum);
    printf("%d",result);
    return 0;
}