Compilare: user.cpp: In function ‘int get_min(int)’: user.cpp:34:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (!visited[y] && v[y].size() < min) { ^ user.cpp:37:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] } else if (v[y].size() == min && !touched[y]) { ^ user.cpp: In function ‘int main()’: user.cpp:81:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("puzzle2.in", "r", stdin); ^ user.cpp:82:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("puzzle2.out", "w", stdout); ^ user.cpp:87:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &N, &M); ^ user.cpp:91:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &a, &b); ^