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