#include "bits/stdc++.h"

using namespace std;

const int maxn=;

int next1[maxn];

char s1[maxn],s2[maxn];

void getnext(char *t){

    int len=strlen(t);

    int i=,j=-;

    next1[]=-;

    while(i<len){

        if(j==- || t[i]==t[j]){

            i++;j++;

            next1[i]=j;

        }else

            j=next1[j];

    }

}

int KMP(char *s,char *t){

    int len1=strlen(s),len2=strlen(t);

    int i=,j=;

    getnext(t);

    while(i<len1 && j<len2){

        if(j==- || s[i]==t[j]){

            i++;j++;

        }else

            j=next1[j];

    }

    if(i==len1)

        return j;

    return ;

}

///KMP返回的就是那个公共子串的长度

int main(){

    //freopen("input.txt","r",stdin);

    while(~scanf("%s%s",s1,s2)){

        int x=KMP(s1,s2);///s1模式串

        int y=KMP(s2,s1);

        if(x==y){///相等取字典序小的

            if(strcmp(s1,s2)<)

                printf("%s%s\n",s1,s2+x);

            else

                printf("%s%s\n",s2,s1+x);

        }else if(x>y)///取合并后短的

            printf("%s%s\n",s1,s2+x);

        else

            printf("%s%s\n",s2,s1+y);

    }

    return ;

}