Untitled

#include <iostream>
#include <string>
#include <iomanip>
#include <cmath>
using namespace std;

int main()
{
	int a = 0;
	int b = 0;
	int razn = 0;
	cin >> a >> b;
	if (a < 0 && a % 2 != 0 
		&& b > 0 && b%2==0) {
		razn = b - a;
		cout << razn;
	}
	else
		cout << "NO";
	}