/in/foo.cc: In function 'int main()':
/in/foo.cc:14:14: warning: variable 'temp' set but not used [-Wunused-but-set-variable]
  int a[maxn],temp;
              ^~~~
/in/foo.cc:21:6: warning: unused variable 'm2' [-Wunused-variable]
  int m2=b[2]/2,m3=b[3],m4=b[4];
      ^~
/in/foo.cc:21:16: warning: unused variable 'm3' [-Wunused-variable]
  int m2=b[2]/2,m3=b[3],m4=b[4];
                ^~
/in/foo.cc:21:24: warning: unused variable 'm4' [-Wunused-variable]
  int m2=b[2]/2,m3=b[3],m4=b[4];
                        ^~