Compilare: user.cpp: In function ‘int main()’: user.cpp:139:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < unions[i].size(); j++) { ^ user.cpp:91:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("unlock.in", "r", stdin); ^ user.cpp:92:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("unlock.out", "w", stdout); ^ user.cpp:93:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &t); ^ user.cpp:96:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &n, &m, &k); ^ user.cpp:99:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &mat[i][j]); ^