vector<int>v;
stack<int>s;

for(int i=0;i<n;i++)
{
   if(s.size()==0)
   {
      v.push_back(-1);
   }
   else if(s.size()>0&&s.top()>arr[i])
   {
      v.push_back(s.top())
   }
   else if(s.size()>0&&s.top()<=arr[i])
   {
      while(s.size()>0&&s.top<=arr[i])
      {
         s.pop();
      }
      if(s.size()==0)
      {
         v.push_back(-1);
      }
      else{
         v.push_back(s.top());
      }
   }
   s.push(arr[i]);
}