Compilare: user.cpp: In function ‘int main()’: user.cpp:51:24: warning: unused variable ‘x3’ [-Wunused-variable] int x1,y1,i, x2,y2,x3,y3,x4,y4; ^ user.cpp:51:27: warning: unused variable ‘y3’ [-Wunused-variable] int x1,y1,i, x2,y2,x3,y3,x4,y4; ^ user.cpp:51:30: warning: unused variable ‘x4’ [-Wunused-variable] int x1,y1,i, x2,y2,x3,y3,x4,y4; ^ user.cpp:51:33: warning: unused variable ‘y4’ [-Wunused-variable] int x1,y1,i, x2,y2,x3,y3,x4,y4; ^ user.cpp:49:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("geometry.in","r",stdin); ^ user.cpp:50:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("geometry.out","w",stdout); ^ user.cpp:54:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:57:42: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d",&x1,&y1,&x2,&y2); ^