#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>   // for isalpha()
int main() {
    int n;
    scanf("%d", &n);
    if (n < 0) {
        printf("Invalid input\n");
        return 0;
    }
    // Allocate memory dynamically for n characters
    char arr = (char)malloc(sizeof(char)*n);
    char *p = arr;  // pointer to traverse
    int sumEven = 0, sumOdd = 0;
    for (int i = 0; i < n; i++) {
        scanf(" %c", p);  // read character into allocated memory
        if (!isalpha(*p)) {  // cursed symbol check
            printf("Invalid input\n");
            free(arr);   // free memory before exiting
            return 0;
        }
        if (((int)(*p)) % 2 == 0) {
            sumEven += (int)(*p); // also sumEven = sumEven + (int)(*p);
        } 
        else {
            sumOdd += (int)(*p);
        }
        p++;  // move pointer forward
    }
    printf("%d\n", abs(sumEven - sumOdd));
    free(arr);  // release allocated memory
    return 0;
}