/in/foo.cc: In function 'int main()':
/in/foo.cc:7:12: warning: unused variable 'u' [-Wunused-variable]
  int num,i,u;  
            ^
/in/foo.cc:9:23: warning: unused variable 'r' [-Wunused-variable]
     int m[num],n[num],r[num],a,b,c,d;  
                       ^
/in/foo.cc:9:30: warning: unused variable 'a' [-Wunused-variable]
     int m[num],n[num],r[num],a,b,c,d;  
                              ^
/in/foo.cc:9:32: warning: unused variable 'b' [-Wunused-variable]
     int m[num],n[num],r[num],a,b,c,d;  
                                ^
/in/foo.cc:9:34: warning: unused variable 'c' [-Wunused-variable]
     int m[num],n[num],r[num],a,b,c,d;  
                                  ^
/in/foo.cc:9:36: warning: unused variable 'd' [-Wunused-variable]
     int m[num],n[num],r[num],a,b,c,d;  
                                    ^