题解及证明：http://www.cnblogs.com/StupidBoy/p/5241258.html

#include
     
      #include
      
       using namespace std;int n,m,a[100100],b[100100];int main(){	//freopen("h.in","r",stdin);	scanf("%d%d",&n,&m);	for(int i=1;i<=n;++i)	  scanf("%d",&a[i]);	for(int i=1;i<=m;++i)	  scanf("%d",&b[i]);	int ans=0;	for(int i=2;i