/in/foo.cc: In function 'void sou()':
/in/foo.cc:16:9: warning: statement has no effect [-Wunused-value]
   cun[i]-1;ans++;sou();if(!flag)ans--;
   ~~~~~~^~
/in/foo.cc:17:9: warning: statement has no effect [-Wunused-value]
   cun[i]+2;ans++;sou();if(!flag)ans--;
   ~~~~~~^~
/in/foo.cc:18:9: warning: statement has no effect [-Wunused-value]
   cun[i]-1;
   ~~~~~~^~