#include <iostream>
using namespace std;
int
ans[201][201], l1, l2;
string
str1, str2, strr[201][201];
void
__read__()
{
cin >> str1 >> str2;
}
void
__init__()
{
for( int i = 0; i <= 200; i++ )
for( int j = 0; j <= 200; j++ )
strr[i][j] = "";
l1 = str1.length();
l2 = str2.length();
memset( ans, 0, sizeof ans );
}
void
__dp__()
{
for( int i = 1; i <= l1; i++ )
for( int j = 1; j <= l2; j++ )
if( str1[i - 1] == str2[j - 1] )
{
ans[i][j] = ans[i - 1][j - 1] + 1;
strr[i][j] = strr[i - 1][j - 1] + str1[i - 1];
}
else
{
if( ans[i - 1][j] > ans[i][j - 1] )
{
ans[i][j] = ans[i - 1][j];
strr[i][j] = strr[i - 1][j];
}
else
{
ans[i][j] = ans[i][j - 1];
strr[i][j] = strr[i][j - 1];
}
}
}
void
__outp__()
{
cout << ans[l1][l2] << endl << strr[l1][l2] << endl;
}
int
main()
{
__read__();
__init__();
__dp__();
__outp__();
return 0;
}