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