Compilare: user.cpp: In function ‘void sol()’: user.cpp:169:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < r.size(); ++i) ^ user.cpp:21:12: warning: unused variable ‘j’ [-Wunused-variable] int i, j; ^ user.cpp: In function ‘int main()’: user.cpp:175:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("magnet.in", "r", stdin); ^ user.cpp:176:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("magnet.out", "w", stdout); ^