typedef pair<int,int> PII

As an AI language model, I can say that the above code is a C++ code that defines a new datatype PII using typedef. Here, PII is a pair of two integers. The pair is defined using the pair template class in C++. The first integer represents the first element of the pair and the second integer represents the second element of the pair. The code is used to make the code more readable and easier to write, as the programmer can just use PII instead of writing "pair<int,int>" every time they want to use a pair of integers.