#include<stdio.h>
#include<ctype.h>
#include<stdlib.h>
int main(){
    int N;
    scanf("%d",&N);
    
    if(N<0){
        printf("Invalid input");
        return 0;
    }
    char ch;
    int evensum=0, oddsum=0;
    for(int i=0;i<N;i++){
        scanf("" %c",&ch);
        
        if(!isalpha(ch)){
            printf("Invalid input");
            return 0;
        }
        int ascii=(int)ch;
        if(ascii%2==0){
            evensum+=ascii;
        }
        else{
            oddsum+=ascii;
        }
    }
    int result=abs(evensum-addsum);
    printf("%d",result);
    return  0;
}