import java.io.*;
class quattro {
	public static void main(String[] args) {
		int posB = 1, posC = 2, posD = 3;
		for(int pos = 0; pos<4; pos++) 
			switch(pos) {
				default:
					System.out.println("a");
					continue;
				case 1:
					System.out.println("b");
					continue;
				case 2:
					System.out.println("c");
					continue;
				case 3:
					System.out.println("d");
					return;
			}
	}
}