Compilare: user.cpp: In function ‘void df(int)’: user.cpp:16:9: warning: unused variable ‘k’ [-Wunused-variable] int k,j,nr=v[i].size(),fiu; ^ user.cpp: In function ‘int main()’: user.cpp:50:15: warning: variable ‘r’ set but not used [-Wunused-but-set-variable] int i,x,y,r,rr,j; ^ user.cpp:48:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("biconex.in","r",stdin); ^ user.cpp:49:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("biconex.out","w",stdout); ^ user.cpp:51:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.cpp:53:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&x,&y); ^