Compilare: user.cpp: In function ‘int main()’: user.cpp:33:15: warning: statement has no effect [-Wunused-value] for(in; fi!=in; in++) ^ user.cpp:53:15: warning: statement has no effect [-Wunused-value] for(in; fi!=in; in++) ^ user.cpp:11:23: warning: variable ‘c’ set but not used [-Wunused-but-set-variable] int n,m,x,y,a,b,i,c,z,k=0,j,ok; ^ user.cpp:11:25: warning: unused variable ‘z’ [-Wunused-variable] int n,m,x,y,a,b,i,c,z,k=0,j,ok; ^ user.cpp:9:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("graf.in","r",stdin); ^ user.cpp:10:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("graf.out","w",stdout); ^ user.cpp:15:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d",&n,&m,&x,&y); ^ user.cpp:18:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&a,&b); ^