import java.io.*;
import java.util.*;

public class subseq {
	public static final Scanner cin = new Scanner(System.in);

	public static void main(String[] args) {
		while(true) {
			String s = cin.nextLine();
			if(s.equals("#END")) { break; }
			System.out.println(Solver.solve(s));
		}
	}

	private static class Solver {
		private String str;

		private static final int DIR_H = 1;
		private static final int DIR_V = 2;
		private static final int DIR_D = 3; // diagonal

		private Solver(String str) {
			this.str = str;
		}

		private static String lcs(String s, String t) {
			int m = s.length();
			int n = t.length();

			int[][] num = new int[m+1][n+1];
			int[][] dir = new int[m+1][n+1];

			for(int i = 1; i <= m; i++) {
				for(int j = 1; j <= n; j++) {
					num[i][j] = -1;
					dir[i][j] = 0;

					if(num[i][j] < num[i-1][j]) { num[i][j] = num[i-1][j]; dir[i][j] = DIR_H; }
					if(num[i][j] < num[i][j-1]) { num[i][j] = num[i][j-1]; dir[i][j] = DIR_V; }

					if(s.charAt(i-1) == t.charAt(j-1)) {
						if(num[i][j] < num[i-1][j-1] + 1) { num[i][j] = num[i-1][j-1] + 1; dir[i][j] = DIR_D; }
					}
				}
			}

			StringBuilder sb = new StringBuilder();

			{
				int i = m;
				int j = n;
				while(i > 0 && j > 0) {
					switch(dir[i][j]) {
						case DIR_H: i--; break;
						case DIR_V: j--; break;
						case DIR_D: i--; j--; sb.append(s.charAt(i)); break;
					}
				}
			}

			sb.reverse();
			return sb.toString();
		}

		private String solve() {
			String ans = "";
			for(int i = 1; i < str.length(); i++) {
				String tmp = lcs(str.substring(0, i), str.substring(i));
				if(ans.length() < tmp.length()) { ans = tmp; }
			}
			return ans;
		}

		public static String solve(String str) {
			return new Solver(str).solve();
		}
	}
}