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

int main(){
    int n;
    scanf("%d", &n);
    if(n < 1 || n > 100) {
        printf("Invalid input\n");
        return 0;
    }
    char initials[101];
    int even_sum = 0, odd_sum = 0;
    
    for(int i = 0; i < n; i++) {
        scanf(" %c" , &initials[i]);
        
        if(!isalpha(initials[i])){
            printf("Invalid input\n");
            return 0;
        }
        char *ptr = &initials[i];
        int ascii_value = (int)(*ptr);
        
        if(ascii_val % 2 == 0)
           even_sum += ascii_val;
        else
           odd_sum += ascii_val;
           
    }
    int result = abs(even_sum - odd_sum);
    printf("%d\n", result);
    return 0;
}