#include<stdio.h>
#include <ctype.h>
#include<stdlib.h>
int main() {
    int N, i;
    char ch;
    int evenSum = 0, oddSum = 0;
    int invalid = 0;
    scanf("%d", &N);
    if (N < 0) {
        printf("Invalid input");
        return 0;
    }
    char initials[100];
    char *p = initials;
    for (i = 0; i < N; i++) {
        scanf(" %c", &ch);
        if (!salpha((unsigned char)ch)){
            
        }
        *(p + i) = ch;
    }
    if (invalid) {
        printf("Invalid input");
        return 0;
    }
    for (i = 0; i < N; i++) {
        int ascii = (int)*(p + i);
        if (ascii % 2 == 0)
          evenSum += ascii;
        else
          oddSum += ascii
    }
    int diff = abs(evenSum - oddSum);
    printf("%d", diff);
    return 0;
    
}