Compilare: user.cpp: In function ‘int main()’: user.cpp:68:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < ctc.size(); ++ i, printf("\n")) ^ user.cpp:69:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < ctc[i].size(); ++ j) ^ user.cpp:42:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.in", "r", stdin); ^ user.cpp:43:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.out", "w", stdout); ^ user.cpp:45:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i %i", &n, &m); ^ user.cpp:48:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i %i", &x, &y); ^