#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
int main() 
{
    int n;
    if (scanf("%d",&n)!=1|| n<1)
    {
        printf("Invalid input");
        return 0;
    }
    char in[100];
    char *ptr = in;
    int even=0, odd=0;
    for (int i=0;i<n;i++)
    {
        char ch;
        scanf(" %c",&ch);
        if (!isalpha(ch))
        {
            printf("Invalid input");
            return 0;
        }
        *(ptr + i) = ch;
        int ascii=(int)*(ptr+i);
        if (ascii%2==0)
        {
            even+=ascii;
        }
        else
        {
            odd_sum += ascii_val;
        }
    }
    int diff=abs(even-odd);
    printf("%d\n", diff);
}