#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define N (300)

#define min(a,b) (((a)<(b))?(a):(b))
#define max(a,b) (((a)>(b))?(a):(b))

static char str[N+2], ans[N+2];
static int  nstr, nans;

void lcs(int n)
{
	static int table[N+1][N+1];
	int i, j, m;
	char *p;

	m = nstr - n;

	for(i = 0; i <= n; i++) { table[i][0] = 0; }
	for(j = 0; j <= m; j++) { table[0][j] = 0; }

	for(i = 0; i < n; i++) {
		for(j = 0; j < m; j++) {
			if(str[i] == str[n + j]) {
				table[i+1][j+1] = table[i][j] + 1;
			}
			else {
				table[i+1][j+1] = max(table[i+1][j], table[i][j+1]);
			}
		}
	}

	if(nans >= table[n][m]) { return; }

	nans = table[n][m];

	i = n - 1;
	j = m - 1;
	p = ans + nans;
	*p = '\0';

	while(i >= 0 && j >= 0) {
		if(str[i] == str[n + j]) {
			*(--p) = str[i];
			i--;
			j--;
		}
		else {
			if(table[i+1][j] > table[i][j+1]) { j--; } else { i--; }
		}
	}
}

int main(void)
{
	int i;

	while(1) {
		fgets(str, sizeof(str), stdin);
		nstr = strlen(str);
		str[--nstr] = '\0';
		if(strcmp(str, "#END") == 0) { return 0; }
		nans = 0;
		for(i = 0; i < nstr; i++) { lcs(i); }
		printf("%s\n", ans);
	}
}