#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("Ivalid input\n");
        return 0;
    }    
 }
   
   char *ptr = arr;
  
  for (int i =0; i < n; i++) {
      if ascii = (int)*(ptr + i);
      if (ascii % 2 ==0)
          evensum += ascii;
        else
        oddsum += ascii;
  }
  printf("%d\n", abs(evensum - oddsum));
  return 0;
  }