# include <bits/stdc++.h>
using namespace std;
using ll=long long;
int a[100010],b[100010];
struct Frac
{
	ll a;int b;
	Frac(){}
	Frac(ll a,int b):a(a),b(b){}
	Frac &operator+=(const Frac &t){a+=t.a;b+=t.b;return *this;}
	bool operator<(const Frac &t)const{return (ll)a*t.b<(ll)b*t.a;}
}stk1[100010];
struct Point
{
	int x,y;
	Point(){}
	Point(int x,int y):x(x),y(y){}
	Point operator-(const Point &t)const{return Point(x-t.x,y-t.y);}
	ll operator*(const Point &t)const{return (ll)x*t.y-(ll)y*t.x;}
	ll operator()(const Frac &t)const{return t.b*y-t.a*x;}
}stk2[100010];
int main()
{
	int n,m,tp1=0,tp2=0;
	cin>>n>>m;
	for(int i=1;i<=n;i++) scanf("%d",&a[i]);
	for(int i=1;i<=m;i++) scanf("%d",&b[i]);
	for(int i=1;i<n;i++) a[i]=a[i+1]-a[i];
	for(int i=1;i<n;i++)
	{
		Frac cur(a[i],1);
		for(;tp1 && cur<stk1[tp1];tp1--) cur+=stk1[tp1];
		stk1[++tp1]=cur;
	}
	for(int i=1;i<=m;i++)
	{
		Point cur(i-1,b[i]);
		while(tp2>1 && (cur-stk2[tp2])*(stk2[tp2]-stk2[tp2-1])>=0) tp2--;
		stk2[++tp2]=cur;
	}
	ll ans=(ll)a[n]*(m-1);
	for(int i=1,j=1;i<=tp1;i++)
	{
		while(j<tp2 && stk2[j+1](stk1[i])<stk2[j](stk1[i])) j++;
		ans+=stk2[j](stk1[i]);
	}
	cout<<ans<<endl;
	return 0;
}