Case of Matryoshkas
Andrewid the Android is a galaxy-famous detective. He is now investigating the case of vandalism at the exhibition of contemporary art.
The main exhibit is a construction of n matryoshka dolls that can be nested one into another. The matryoshka dolls are numbered from 1 to n. A matryoshka with a smaller number can be nested in a matryoshka with a higher number, two matryoshkas can not be directly nested in the same doll, but there may be chain nestings, for example, 1 → 2 → 4 → 5.
In one second, you can perform one of the two following operations:
Having a matryoshka a that isn’t nested in any other matryoshka and a matryoshka b, such that b doesn’t contain any other matryoshka and is not nested in any other matryoshka, you may put a in b;
Having a matryoshka a directly contained in matryoshka b, such that b is not nested in any other matryoshka, you may get a out of b.
According to the modern a