> 
> char str[105][105];
> int len[105];
> int main()
> {
> 	int n,i,j,k;
> 	while(scanf("%d",&n),n)
> 	{
> 		int ans=inf;
> 		for(i=1;i<=n;i++)
> 		{
> 			scanf("%s",str[i]);
> 			len[i]=strlen(str[i]);
> 			checkmin(ans,len[i]-1);
> 		}
> 		for(i=1;i<=n;i++)for(j=i+1;j<=n;j++)if(len[i]==len[j])
> 		{
> 			for(k=len[i]-1;k>=0;k--)if(str[i][k]!=str[j][k])break;
> 			checkmin(ans,k);
> 		}
> 		printf("%d\n",ans);
> 	}
> }