#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
int main(){
    int n,even=0,odd=0;
    scanf("%d",&n);
    if(n,1){printf("Invalid Input");return 0;
    char a[n];
    for(int i=0;i<n;i++{
        scanf("%c",&a[i]);
        if(!isalpha(a[i])){printf("Invalid Input");
        int*p=(int*)&a[i];
        (*p%2==0)?(even+=*p):(odd+=*p);
    }
    printf("%d",abs(even-odd));
    return 0;
}