#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
int main() {
    int N;
    char initials[101];
    if(scanf("%d", &N) != 1) {
        printf("Invalid input");
        return 1;
    }
    if (N < 1 || N > 100) {
        printf("Invalid input");
        return 1;
    }
    scanf(" %[^\n]",initials);
    int even_sum = 0;
    int odd_sum = 0;
    int count = 0;
    for (char *ptr = initials; *ptr != '\0' && count < N; ptr++) {
        if (*ptr = ' ') {
            continue;
        }
        if (!isalpha(*ptr)) {
            printf("Invalid input");
            return 1;
        }
        if ((int)*ptr % 2 == 0) {
            even_sum += (int)*ptr;
        } else {
            odd_sum += (int)*ptr;
        }
        count++;
    }
    if (count != N) {
        printf("Invalid input");
        return 1;
    }
    printf("%d", abs(even_sum - od_sum));
    return 0;
}