#include <iostream>
#include <math.h>

using namespace std;

int main() {
	cout << "pick a number. don't tell me";
	cout << "\n enter an upper bound: ";
	double upper = 0;
	cin >> upper;

	double lower = 0;
	double  middle = 0;

	while (upper - lower > 1) {
		
		middle = floor((lower + upper) / 2);
	
		cout << "is you number greater than " << middle << "? ";
		char input;
		cin >> input;
		if (input == 'y'){
			lower = middle;
		}
		else 
			upper = middle;
	}
	
	cout << "is your number " << upper  << "? ";
	char input;
	cin >> input;
	if (input == 'y')
		cout << "your number is "  << upper;
	else
		cout << "your number is " << lower;
 

}