Compilare: In file included from /usr/include/c++/6/cassert:44:0, from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:33, from main.cpp:1: main.cpp: In member function 'std::vector<int> FFT::multiply(std::vector<int>, std::vector<int>)': main.cpp:65:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] assert(b.size() == n); ~~~~~~~~~^~~~ main.cpp: In function 'void solve()': main.cpp:127:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < c.size(); i++) ~~^~~~~~~~~~