// editor1
#include<stduo.h>
#include<ctype.h>
#include<stdlib.h>
int main()
{
    int N;
    scanf("%d",&N);
    if(N < 0) {
        printf("Invalid input");
        return 0;
    }
    char arr[N];
    char *ptr = arr;
    for (int i=0;i<N;i++) {
        scanf(" %c",(ptr + i));
        if(!isalpha(*(ptr + i))) {
            printf("Invalid input");
            return 0;
        }
    }
    int sumEven = 0,sumOdd = 0;
    for(int i = 0;i < N; i++) {
        int ascii = *(ptr + i);
        if(ascii % 2 == 0)
        sumEven += ascii;
        else
        sumOdd += ascii;
    }
    int diff = abs(sumEven - sumOdd);
    printf("%d",diff);
}