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