Compilare: user.cpp: In function ‘int main()’: user.cpp:75:54: warning: unused variable ‘a1’ [-Wunused-variable] double a, b, c, d1, d2, c1, c2, l, w, ans, area, a1, b1; ^ user.cpp:75:58: warning: unused variable ‘b1’ [-Wunused-variable] double a, b, c, d1, d2, c1, c2, l, w, ans, area, a1, b1; ^ user.cpp:77:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("rubarba.in", "r", stdin); ^ user.cpp:78:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("rubarba.out", "w", stdout); ^ user.cpp:80:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d", &n); ^ user.cpp:83:45: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%lf%lf", &P [i].x, &P [i].y); ^ user.cpp:190:22: warning: ‘ans’ may be used uninitialized in this function [-Wmaybe-uninitialized] if (area - ans <= -eps) ^