Compilare: user.cpp: In function ‘int reunion(int, int)’: user.cpp:33:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:64:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (sol.size() == N - 1) { ^ user.cpp:57:35: warning: unused variable ‘c’ [-Wunused-variable] int x = it->x, y = it->y, c = it->c; ^ user.cpp:36:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("politie.in", "r", stdin); ^ user.cpp:37:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("politie.out", "w", stdout); ^ user.cpp:39:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d", &N, &M, &D, &P); ^ user.cpp:44:42: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d", &x, &y, &c, &p); ^