pat1077

#include<cstdio>#include<iostream>#include<algorithm>#include<vector>#include<queue>#include<string>#include<cstring>#include<cmath>#include<map>#define ll long longusing namespace std;char a[105][300];int l[105];int main(){    int n,i,j,f;while(scanf("%d",&n)!=EOF){getchar();int mn = 1000;for(i = 0;i<n;i++){cin.getline(a[i],299,'\n');l[i] = strlen(a[i]);mn = min(mn,l[i]);}f = 0;for(i = 1;i<=mn;i++){f = 0;char tmp = a[0][l[0]-i];for(j = 1;j<n;j++){if(a[j][l[j]-i]!=tmp){f = 1;break;}}if(f)break;}i--;        if(i == 0)printf("nai\n");        else        {            for(j = l[0]-i;j<l[0];j++)printf("%c",a[0][j]);            printf("\n");        }}    return 0;}