Compilare: main.cpp: In function 'void solve(std::vector<Complex>)': main.cpp:87:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int ptr = -1, i = 0; i < difs.size(); ++i) { ~~^~~~~~~~~~~~~ main.cpp:93:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i - pal[i] >= 0 && i + pal[i] < difs.size() && difs[i - pal[i]] == difs[i + pal[i]]) ~~~~~~~~~~~^~~~~~~~~~~~~ main.cpp:99:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0, st = 0, dr = 1; i < difs.size(); ++i, st+= i % 2, dr+= i % 2) if (2 * pal[i] - 1 >= n - 1) { ~~^~~~~~~~~~~~~ main.cpp: In function 'void filter()': main.cpp:129:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < circles.size() && eq(dirs[i], start)) { ~~^~~~~~~~~~~~~~~~