#include <bits/stdc++.h>
using namespace std;
#define all(x) x.begin(), x.end()
#define ar array
#define pb push_back
#define ln '\n'
#define int long long
using i64 = long long;
template <class F, class _S>
bool chmin(F &u, const _S &v){
bool flag = false;
if ( u > v ){
u = v; flag |= true;
}
return flag;
}
template <class F, class _S>
bool chmax(F &u, const _S &v){
bool flag = false;
if ( u < v ){
u = v; flag |= true;
}
return flag;
}
const int inf = 1e15;
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int h, w; cin >> h >> w;
vector <int> a(h), b(w);
for ( auto &u: a ) cin >> u;
for ( auto &u: b ) cin >> u;
auto get = [&](vector <int> a){
int n = a.size();
vector <int> prfmin(n + 1), sufmin(n + 2);
prfmin[0] = sufmin[n + 1] = inf;
for ( int i = 0; i < n; i++ ){
prfmin[i + 1] = min(prfmin[i], a[i]);
}
for ( int i = n; i > 0; i-- ){
sufmin[i] = min(sufmin[i + 1], a[i - 1]);
}
vector <int> p;
for ( int i = 0; i < n; i++ ){
if ( max(prfmin[i], sufmin[i + 2]) <= a[i] ){
continue;
} p.pb(i);
}
return p;
};
auto idxA = get(a); h = idxA.size();
auto idxB = get(b); w = idxB.size();
vector <vector<int>> dp(h, vector <int> (w, inf));
dp[0][0] = 0;
for ( int i = 0; i < h; i++ ){
for ( int j = !i; j < w; j++ ){
int opt = inf;
if ( i > 0 ) chmin(opt, b[idxB[j]] * (idxA[i] - idxA[i - 1]) + dp[i - 1][j]);
if ( j > 0 ) chmin(opt, a[idxA[i]] * (idxB[j] - idxB[j - 1]) + dp[i][j - 1]);
dp[i][j] = opt;
}
}
cout << dp[h - 1][w - 1];
cout << '\n';
}
