foo.cc:13:19: warning: character constant too long for its type
             print('%d %d'%(i,j))
                   ^~~~~~~
foo.cc:1:1: error: 'n' does not name a type
 n=int(input())
 ^

自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。