#include <bits/stdc++.h>
#define pb push_back
using namespace std;
using ll = long long;
int h, w;
vector<int> a, b;
vector<int> ca, cb;
void load() {
cin >> h >> w;
ca.pb(1), cb.pb(1);
for (int i = 0; i < h; ++i) {
int na;
cin >> na;
while (a.size() >= 2 && a[a.size() - 2] <= a.back() && na <= a.back()) {
a.pop_back();
ca[ca.size() - 2] += ca.back();
ca.pop_back();
}
a.push_back(na);
ca.pb(1);
}
for (int i = 0; i < w; ++i) {
int na;
cin >> na;
while (b.size() >= 2 && b[b.size() - 2] <= b.back() && na <= b.back()) {
b.pop_back();
cb[cb.size() - 2] += cb.back();
cb.pop_back();
}
b.push_back(na);
cb.pb(1);
}
h = size(a);
w = size(b);
}
ll inf = 1ll << 58;
void slowSolve() {
int dh = h + 10;
int dw = w + 10;
ll dp[dh][dw];
for (int i = 0; i < dh; ++i) {
for (int j = 0; j < dw; ++j) dp[i][j] = inf;
}
dp[1][1] = 0;
for (int i = 1; i <= h; ++i) {
for (int j = 1; j <= w; ++j) {
dp[i][j] = min({dp[i][j], dp[i-1][j] + 1ll * ca[i - 1] * b[j-1], dp[i][j-1] + 1ll * cb[j - 1] * a[i-1]});
}
}
cout << dp[h][w] << '\n';
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
load();
slowSolve();
return 0;
}
