/*

 给两个串a,b。输出一个最短的串(含等于a的子序列且含等于b的子序列)

 */

 #include <iostream>

 #include <cstdio>

 #include <cstring>

 using namespace std;

 const int maxn=;

 int dp[maxn][maxn],path[maxn][maxn];

 int len,len1,len2;

 char text[maxn],a[maxn],b[maxn];

 void getpath()

 {

     int n=len,i=len1,j=len2;

     while(n)

     {

         if(path[i][j]==)

             text[n--]=a[i],i--,j--;

         else if(path[i][j]==) i--;

         else j--;

     }

 }

 int main()

 {

     int i,j,k;

     a[]=b[]='';

     while(~scanf("%s%s",a+,b+))

     {

         memset(dp,,sizeof(dp));

         len1=strlen(a)-,len2=strlen(b)-;

         for(i=;i<=len1;i++)

         {

             for(j=;j<=len2;j++)

             {

                 if(a[i]==b[j])dp[i][j]=dp[i-][j-]+,path[i][j]=;

                 else

                 {

                     if(dp[i-][j]>dp[i][j-]) dp[i][j]=dp[i-][j],path[i][j]=;

                     else dp[i][j]=dp[i][j-],path[i][j]=;

                 }

             }

         }

         len=dp[len1][len2];

         getpath();

         j=,k=;

         for(i=;i<=len;i++)

         {

             while(a[j]!=text[i]) printf("%c",a[j++]);

             while(b[k]!=text[i]) printf("%c",b[k++]);

             printf("%c",text[i]);

             j++;k++;

         }

         while(j<=len1) printf("%c",a[j++]);

         while(k<=len2) printf("%c",b[k++]);

         printf("\n");

     }

     return ;

 }