#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
ld inf = 1e18;
struct line{
ll m, c;
};
struct hull{
vector<line> v;
ld poi(line a, line b){
return (ld)(b.c - a.c) / (a.m - b.m);
}
void push(line a){
while (v.size() >= 2 && poi(a, v.back()) < poi(v.back(), v[v.size() - 2])) v.pop_back();
v.push_back(a);
}
ld getbp(){
return (v.size() >= 2 ? poi(v.back(), v[v.size() - 2]) : -inf);
}
};
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
int rows, cols; cin >> rows >> cols;
vector<ll> rv(rows), cv(cols);
for (int i = 0; i < rows; i++) cin >> rv[i];
for (int i = 0; i < cols; i++) cin >> cv[i];
hull rh, ch;
for (int i = rows - 1; i >= 0; i--) rh.push({i, rv[i]});
for (int i = cols - 1; i >= 0; i--) ch.push({i, cv[i]});
ll ans = 0, r = 0, c = 0;
while (r < rows - 1 || c < cols - 1){
if (rh.getbp() > ch.getbp()){
rh.v.pop_back();
ll nr = rh.v.back().m;
ans += (nr - r) * cv[c];
r = nr;
}
else{
ch.v.pop_back();
ll nc = ch.v.back().m;
ans += (nc - c) * rv[r];
c = nc;
}
}
cout << ans;
}
