import java.util.Scanner;

public class FixedCapacityStackOfStrings {
	private String[] a;
	private int N;
	public FixedCapacityStackOfStrings(int cap){
		a=new String[cap];
	}
	public boolean isEmpty() { return N==0; }
	public int size() { return N; }
	public void push(String s){
		a[N++]=s;
	}
	public String pop(){
		return a[--N];
	}
	public static void main(String[] args) {
		FixedCapacityStackOfStrings s=new FixedCapacityStackOfStrings(100);
		Scanner cin=new Scanner(System.in);
		while(cin.hasNext()){
			String str=cin.next();
			if(!str.equals("-")){
				s.push(str);
				System.out.print("push "+str+" ");
			}
			else if(!s.isEmpty()){
				System.out.print("pop  "+s.pop()+" ");
			}
			System.out.println(" | "+s.size()+" left on stack");
		}
	}
}

//test example
to be or not to - be - - that - - - is
push to  | 1 left on stack
push be  | 2 left on stack
push or  | 3 left on stack
push not  | 4 left on stack
push to  | 5 left on stack
pop  to  | 4 left on stack
push be  | 5 left on stack
pop  be  | 4 left on stack
pop  not  | 3 left on stack
push that  | 4 left on stack
pop  that  | 3 left on stack
pop  or  | 2 left on stack
pop  be  | 1 left on stack
push is  | 2 left on stack