Statement

Marco likes very much to play with the sand. He has many tools he uses to build sand castles, like shovels, rakes and molds. He also has N buckets, the i-th of which having a diameter of D_i centimeters. Marco would like to pile the buckets one inside the other to transport them more easily. Of course, one bucket A can be put inside another bucket B only if the diameter of A is strictly smaller than that of B, that is, if D_A < D_B. Help Marco find out if it is possible to put all the buckets in a single pile!