#include<cstdio>

 #include<cstring>

 #include<algorithm>

 #define LL long long

 #define rg register

 #define N 2000

 using namespace std;

 int n,m,tot,f[N][N],from[N][N][];

 char s1[N],s2[N],ans[N];

 int main(){

     scanf("%s",s1+);

     scanf("%s",s2+);

     n=strlen(s1+); m=strlen(s2+);

     for(rg int i=;i<=n;i++)

         for(rg int j=;j<=m;j++)

             if(s1[i]==s2[j]) f[i][j]=f[i-][j-]+,from[i][j][]=i-,from[i][j][]=j-;

             else{

                 if(f[i-][j]>f[i][j-]) f[i][j]=f[i-][j],from[i][j][]=i-,from[i][j][]=j;

                 else f[i][j]=f[i][j-],from[i][j][]=i,from[i][j][]=j-;

             }

     while(n&&m){

         if(s1[n]==s2[m]) ans[++tot]=s1[n];

         int t1=from[n][m][],t2=from[n][m][];

         n=t1,m=t2;

     }

     for(rg int i=tot;i;i--) printf("%c",ans[i]);

     return ;

 }