#include<bits/stdc++.h>
using namespace std;
const int N = 200 + 10;
string a,b,ans;
struct node
{
	int num;
	int i;
	int j;
}dp[N][N];
int main(){
	cin >> a>>b;
	int lena = a.size();
	int lenb = b.size();
	for(int i = 1;i <= lena;i++)
	{
		for(int j = 1;j <= lenb;j++)
		{
	        if(a[i - 1] == b[j - 1])
	        {
	        	dp[i][j].num = dp[i - 1][j - 1].num + 1;
	        	dp[i][j].i = i;
	        	dp[i][j].j = j;
			}
			else if(dp[i - 1][j].num > dp[i][j - 1].num)
			{
	        	dp[i][j].num = dp[i - 1][j].num;
	        	dp[i][j].i = dp[i - 1][j].i;
	        	dp[i][j].j = dp[i - 1][j].j;
			}
			else 
			{
	        	dp[i][j].num = dp[i][j - 1].num;
	        	dp[i][j].i = dp[i][j - 1].i;
	        	dp[i][j].j = dp[i][j - 1].j;
			}
		}
	} 
    cout << dp[lena][lenb].num << endl;
    for(int i = dp[lena][lenb].i,j = dp[lena][lenb].j,tmp;i | j;i = tmp)
    {
    	ans = a[i - 1] + ans;
    	tmp = dp[i - 1][j - 1].i;
    	j = dp[i - 1][j - 1].j;
	}
	cout << ans;
	return 0;
}