/in/foo.cc: In function 'int main()':
/in/foo.cc:12:28: warning: unused variable 'ci' [-Wunused-variable]
     int n,i,left,right,mid,ci,m,last=1,haha=0,ans;
                            ^~
/in/foo.cc:12:33: warning: unused variable 'last' [-Wunused-variable]
     int n,i,left,right,mid,ci,m,last=1,haha=0,ans;
                                 ^~~~
/in/foo.cc:77:13: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
    cout<<ans;
             ^