#define maxn 200010int wa[maxn],wb[maxn],wv[maxn],ws[maxn];int cmp(int *r,int a,int b,int l){return r[a]==r[b]&&r[a+l]==r[b+l];}//yuan lai zhi qian ba zhe li de l cuo dang cheng 1 le ...void da(int *r,int *sa,int n,int m){    int i,j,p,*x=wa,*y=wb,*t;    for(i=0;i<m;i++)ws[i]=0;    for(i=0;i<n;i++)ws[x[i]=r[i]]++;    for(i=1;i<m;i++)ws[i]+=ws[i-1];    for(i=n-1;i>=0;i--)sa[--ws[x[i]]]=i;    for(j=1,p=1;p<n;j*=2,m=p)    {        for(p=0,i=n-j;i<n;i++)y[p++]=i;        for(i=0;i<n;i++)if(sa[i]>=j) y[p++]=sa[i]-j;        for(i=0;i<n;i++)wv[i]=x[y[i]];        for(i=0;i<m;i++)ws[i]=0;        for(i=0;i<n;i++)ws[wv[i]]++;        for(i=1;i<m;i++)ws[i]+=ws[i-1];        for(i=n-1;i>=0;i--)sa[--ws[wv[i]]]=y[i];        for(t=x,x=y,y=t,p=1,x[sa[0]]=0,i=1;i<n;i++)            x[sa[i]]=cmp(y,sa[i-1],sa[i],j)? (p-1):p++;    }}int rankk[maxn],height[maxn];void calheight(int *r,int *sa,int n){    int i,j,k=0;    for(i=1;i<=n;i++)rankk[sa[i]]=i;    for(i=0;i<n;height[rankk[i++]]=k)        for(k? k--:0,j=sa[rankk[i]-1];r[i+k]==r[j+k];k++);}int RMQ[maxn];int mm[maxn];int best[20][maxn];void initRMQ(int n){    int i,j,a,b;    for(mm[0]=-1,i=1;i<=n;i++)        mm[i]=((i&(i-1))==0) ? mm[i-1]+1:mm[i-1];    for(i=1;i<=n;i++)best[0][i]=i;    for(i=1;i<=mm[n];i++)        for(j=1;j<=n+1-(1<<i);j++)        {            a=best[i-1][j];            b=best[i-1][j+(1<<(i-1))];            if(RMQ[a]<RMQ[b])best[i][j]=a;            else best[i][j]=b;        }}int askRMQ(int a,int b){    int t;    t=mm[b-a+1];b-=(1<<t)-1;    a=best[t][a];b=best[t][b];    return RMQ[a]<RMQ[b]? a:b;}int lcp(int a,int b){    int t;    a=rankk[a]; b=rankk[b];    if(a>b) {t=a;a=b;b=t;}    return (height[askRMQ(a+1,b)]);}    char s[maxn];    int r[maxn],sa[maxn];int main(){    int t;    while(scanf("%d",&t)!=EOF)    {        scanf("%s",s);        int len1=strlen(s);        s[len1]=‘0‘;//yin wei bu ce ng chu xian ,suo yi bu yong dan xin ying xiang jie guo        scanf("%s",s+len1+1);        int len2=strlen(s);        for(int i=0;i<len2;i++)r[i]=s[i];//r[i]biao shi pai de shi di ji        r[len2]=0;//ji shu pai xu shi de xu yao ,zui hou yi ge jia she wei zui xiao        da(r,sa,len2+1,130);        calheight(r,sa,len2);        int ans=0,be=-1;        //bian li height shu zu, cong di 2 ge kai shi (xia biao shi cong 1 kai shi de )        for(int i=2;i<=len2;i++)        {            if(height[i]>ans)            {                if((len1<sa[i]&&len1>sa[i-1])||(len1>sa[i]&&len1<sa[i-1]))                {                    ans=height[i];be=sa[i];                }            }        }        if(be!=-1)            for(int i=be;i<be+ans;i++)printf("%c",s[i]);        printf("\n");    }    return 0;}