Compilare: user.cpp: In function ‘int main()’: user.cpp:24:12: warning: unused variable ‘a’ [-Wunused-variable] double a,b,c; ^ user.cpp:24:14: warning: unused variable ‘b’ [-Wunused-variable] double a,b,c; ^ user.cpp:24:16: warning: unused variable ‘c’ [-Wunused-variable] double a,b,c; ^ user.cpp:20:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hawaii.in","r",stdin); ^ user.cpp:21:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hawaii.out","w",stdout); ^ user.cpp:25:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&n,&xg,&yg); ^ user.cpp:27:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&x,&y); ^