Compilare: user.cpp: In function ‘int main()’: user.cpp:65:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 1 ; i < r.size() ; i ++) ^ user.cpp:83:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 1 ; i < l.size() ; i ++) ^ user.cpp:19:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rays.in" , "r" , stdin); ^ user.cpp:20:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rays.out" , "w" , stdout); ^ user.cpp:23:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &n); ^ user.cpp:27:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d" , &x , &y1 , &y2); ^