/in/foo.cc: In function 'int main()':
/in/foo.cc:11:12: error: 'n' was not declared in this scope
  for(int i=n;cin>>n)
            ^
/in/foo.cc:11:20: error: expected ';' before ')' token
  for(int i=n;cin>>n)
                    ^
/in/foo.cc:16:15: error: 'setw' was not declared in this scope
   cout<<setw(3)<<a[i][0];
               ^
/in/foo.cc:11:10: warning: unused variable 'i' [-Wunused-variable]
  for(int i=n;cin>>n)
          ^