#include <iostream>
#define PP(x)                  std :: cout << #x << ":" << (x) << std :: endl
#define PP2(x,y)               std :: cout << #x << ',' << #y << ":\t" << (x) << " , " << (y) << std :: endl
#define PP3(x,y,z)             std :: cout << #x << ',' << #y << ',' << #z                              << ":\t" << (x) << " , " << (y) << " , " << (z) << std :: endl
#define PP4(x,y,z,w)           std :: cout << #x << ',' << #y << ',' << #z << ',' << #w                 << ":\t" << (x) << " , " << (y) << " , " << (z) << " , " << w << std :: endl
#define unless(x) if(!(x))
