#include<stdio.h>
#include<ctype.h>
#include<stdlib.h>

int main(){
    int N;
    scanf("%d",&N);
    
    if(N<=0){
        printf("Invalid input");
        return 0;
    }
    char arr[101];
    int *ptrEven, *ptrOdd;
    int evenSum=0, oddSum=0;
    
    for(int i=0;i<N;i++){
        scanf(" %c",&arr[i]);
        
        if(!isalpha(arr[i]))
         printf("Invalid input");
         return 0;
    }
        int ascii=(int)arr[i];
        
        if(ascii%2==0)
         ptrEven =&evenSum, *ptrEven+=ascii;
         else
         ptrEven=&oddSum, *ptrOdd+=ascii;
    }
    printf("%d",abs(evenSum-oddSum));
    
    return 0;
    
}