#include<stdio.h>
#include<stdlib.h>
#include<ctype.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("%d\n" , abs(evensum - oddsum));

return 0;
}