Compilare: main.cpp: In function 'int main()': main.cpp:71:37: warning: narrowing conversion of 'qry.std::vector<_Tp, _Alloc>::size<Op, std::allocator<Op> >()' from 'std::vector<Op>::size_type {aka long unsigned int}' to 'int' inside { } [-Wnarrowing] qry.pb ({x, y, qry.size ()}); ~~~~~~~~~^~ main.cpp:82:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < qry.size (); i++) ~~^~~~~~~~~~~~~ main.cpp:49:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("undo.in", "r", stdin); ^ main.cpp:50:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("undo.out", "w", stdout); ^