#include <bits/stdc++.h>
#define F first
#define S second
#define pb push_back
#define ppb pop_back
#define ep insert
#define endl '\n'
#define elif else if
#define pow pwr
#define sqrt sqrtt
#define int long long
#define ll long long
#define y1 YONE
typedef unsigned long long ull;
using namespace std;
const int N=1005;
int n,m,a[N],b[N],dp[N];
int32_t main(){
ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
cin>>n>>m;
for (int i=1;i<=n;i++) cin>>a[i];
for (int i=1;i<=m;i++) cin>>b[i];
for (int i=1;i<=m;i++) dp[i]=a[1]*(i-1);
for (int i=2;i<=n;i++){
dp[1]+=b[1];
for (int j=2;j<=m;j++) dp[j]=min(dp[j-1]+a[i],dp[j]+b[j]);
}
cout<<dp[m]<<endl;
return 0;
}
