public class Solution extends GuessGame {
    public int guessNumber(int n) {
        int l=1, r=n, mid;
        while(l<=r){
            mid=l+(r-l)/2;
            if(guess(mid)==0) return mid;
            if(guess(mid)==1) l=mid+1;
            if(guess(mid)==-1) r=mid-1;
        }
        
        return l;
    }
}