Compilare: user.cpp: In function ‘int main()’: user.cpp:22:11: warning: unused variable ‘a’ [-Wunused-variable] int n,a,b,s = 0,x,y; ^ user.cpp:22:13: warning: unused variable ‘b’ [-Wunused-variable] int n,a,b,s = 0,x,y; ^ user.cpp:20:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("heavymetal.in", "r",stdin); ^ user.cpp:21:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("heavymetal.out", "w",stdout); ^ user.cpp:23:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:25:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &v[i].x, &v[i].y); ^