class Fronta {
	private char f_pole[];
	private int zacatek, konec;
	final int pSize = 20;
	
	public Fronta() {
		this.f_pole = new char[this.pSize];
		zacatek = konec = 0;
	}
	
	public void Push(char znak) {
		this.f_pole[this.konec++] = znak;
		this.konec = this.konec % this.f_pole.length;
	}
	
	public char Pop() {
		char znak = this.f_pole[this.zacatek++];
		this.zacatek = this.zacatek % this.f_pole.length;
		return znak;
	}
	
	public boolean isEmpty() {
		return (this.zacatek == this.konec);
	}
	
	public String PrintContent() {
		String obsah = new String();
		int i = this.zacatek;
		
		while (this.konec!=i) {
			obsah+=(++i) + " ";
			i = i % this.f_pole.length;
		}
		return obsah;
	}
}

public class Pr02 {
	public static void Tiskni(String line) {
		System.out.println(line);
	}
	
	public static void Tiskni(String line, boolean newline) {
		if (newline) {
			System.out.println(line);
		} else {
			System.out.print(line);
		}
	}
	
	public static void main(String[] args) {
		char znak, popznak;
		boolean isErr = false;
		
		Fronta queue = new Fronta();
		String radek = VstupData.ctiString();
		
		for(int i=0;i<radek.length();i++) {
			znak = radek.charAt(i);
			
			if (znak == 'p') {
				queue.Push(znak);
				Tiskni(queue.PrintContent());
			} else if (znak == 'o') {
				if (!queue.isEmpty()) {
					popznak = queue.Pop();
					if (queue.isEmpty()) {
						Tiskni("Fronta je prazdna.");
					} else {
						Tiskni(queue.PrintContent());
					}
				} else {
					isErr = true;
					Tiskni("Chyba - fronta je prazdna.");
					break;
				}
			}
		}
		if (!isErr) Tiskni("Fronta je prazdna.");
	}
}