Compilare: user.cpp: In function ‘void read()’: user.cpp:22:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < a.size(); i++) ^ user.cpp:6:11: warning: unused variable ‘first’ [-Wunused-variable] #define x first ^ user.cpp:18:12: note: in expansion of macro ‘x’ int n, x, y; ^ user.cpp:7:11: warning: unused variable ‘second’ [-Wunused-variable] #define y second ^ user.cpp:18:15: note: in expansion of macro ‘y’ int n, x, y; ^ user.cpp: In function ‘double solve()’: user.cpp:43:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < a.size(); i++) ^ user.cpp:44:63: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = i + 1; a[j].x - a[i].x < d && j < a.size(); j++) ^