/in/foo.cc: In function 'int main()':
/in/foo.cc:14:21: warning: unused variable 'temp' [-Wunused-variable]
  int data[maxn];int temp[maxn];
                     ^~~~
/in/foo.cc:20:6: warning: unused variable 'cost' [-Wunused-variable]
  int cost=0;
      ^~~~
/in/foo.cc:21:7: warning: unused variable 'flag' [-Wunused-variable]
  bool flag=true;
       ^~~~
/in/foo.cc:22:6: warning: unused variable 'pdata' [-Wunused-variable]
  int pdata=0,ptemp=0;
      ^~~~~
/in/foo.cc:22:14: warning: unused variable 'ptemp' [-Wunused-variable]
  int pdata=0,ptemp=0;
              ^~~~~