Compilare: user.cpp: In function ‘void solve()’: user.cpp:65:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (g[i].size() == n - 1) ^ user.cpp: In function ‘void read()’: user.cpp:21:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] { scanf("%d %d", &n, &m); ^ user.cpp:25:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] { scanf("%d%d", &x, &y); ^ user.cpp: In function ‘int main()’: user.cpp:94:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] { freopen("divisorgraph.in", "r", stdin); ^ user.cpp:95:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("divisorgraph.out", "w", stdout); ^ user.cpp:98:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &t); ^