#include <studio.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("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;
    }
    
    prinf("%d\n",abs(evenSum -oddSum));
    
    return 0;
}