// Use suffix array and LCP to compute
// longest common substring of two input strings. BPW

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

char s[1000000],s1[500000],s2[500000];
int n,           // length of s[] including \0
  sa[1000000],   // suffix array for s[]
  rank[1000000], // rank[i] gives the rank (subscript) of s[i] in sa[]
  lcp[1000000];  // lcp[i] indicates the number of identical prefix symbols
                 // for s[sa[i-1]] and s[sa[i]]

int suffixCompare(const void *xVoidPt,const void *yVoidPt)
{
// Used in qsort call to generate suffix array.
int *xPt=(int*) xVoidPt,*yPt=(int*) yVoidPt;

return strcmp(&s[*xPt],&s[*yPt]);
}

void computeRank()
{
// Computes rank as the inverse permutation of the suffix array
int i;

for (i=0;i<n;i++)
  rank[sa[i]]=i;
}

void computeLCP()
{
//Kasai et al linear-time construction
int h,i,j,k;

h=0;  // Index to support result that lcp[rank[i]]>=lcp[rank[i-1]]-1
for (i=0;i<n;i++)
{
  k=rank[i];
  if (k==0)
    lcp[k]=(-1);
  else
  {
    j=sa[k-1];
    // Attempt to extend lcp
    while (i+h<n && j+h<n && s[i+h]==s[j+h])
      h++;
    lcp[k]=h;
  }
  if (h>0)
    h--;  // Decrease according to result
}
}

int fibIndex=0;

void fib(k)
int k;
{
if (k==0)
  s[fibIndex++]='1';
else if (k==1)
  s[fibIndex++]='0';
else
{
  fib(k-1);
  fib(k-2);
}
}

int main()
{
int i,j,k,p,dollarPos,LCSpos=0,LCSlength=0;


scanf("%s",s1);
scanf("%s",s2);

for (i=0;s1[i]!='\0';i++)
  s[i]=s1[i];
dollarPos=i;
s[i++]='$';
for (j=0;s2[j]!='\0';j++)
  s[i+j]=s2[j];
s[i+j]='\0';
n=i+j+1;

/*
fib(4);
fib(6);
dollarPos=fibIndex;
s[fibIndex++]='$';
fib(5);
fib(7);
s[fibIndex]='\0';
n=fibIndex+1;
*/


/*
for (i=0;i<1000;i++)
  s[i]='a';
s[1000]='b';
s[1001]='\0';
*/
/*
s[0]='a';
for (i=1;i<1000;i++)
  s[i]='b';
s[1000]='\0';
*/

//n=strlen(s)+1;
printf("n is %d\n",n);

// Quick-and-dirty suffix array construction
for (i=0;i<n;i++)
  sa[i]=i;
qsort(sa,n,sizeof(int),suffixCompare);
computeRank();
computeLCP();
if (n<200)
{
  printf("i   sa  suffix                              lcp s rank lcp[rank]\n");
  for (i=0;i<n;i++)
    printf("%-3d %-3d %-35.35s %-3d %c  %-3d  %-3d\n",
      i,sa[i],&s[sa[i]],lcp[i],s[i],rank[i],lcp[rank[i]]);
}

for (i=1;i<n;i++)
  if (  (sa[i-1]<dollarPos && sa[i]>dollarPos
        ||  sa[i-1]>dollarPos && sa[i]<dollarPos)
  && lcp[i]>LCSlength)
  {
    LCSpos=i;
    LCSlength=lcp[i];
  }
printf("Length of longest common substring is %d\n",LCSlength);
printf("at position %d\n",LCSpos);
for (i=0;i<LCSlength;i++)
  printf("%c",s[sa[LCSpos]+i]);
printf("\n");
}