#include <bits/stdc++.h>
using namespace std;
void run_case() {
  int n, m;
  cin >> n >> m;
  std::vector<int> a(n), b(m);
  for (auto &i : a) {
    cin >> i;
  }
  for (auto &i : b) {
    cin >> i;
  }
  long long mn = 0;
  sort(a.rbegin(), a.rend());
  sort(b.begin(), b.end());
  if (a[0] > b[0]) {
    cout << -1;
    return;
  }
  long long ans = 0;
  for (int i : a) {
    ans += (long long)i * m;
  }
  for (int i : b) {
    ans += i - a[0];
  }
  if (b[0] > a[0]) {
    ans += (a[0] - a[1]);
  }
  cout << ans;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  int tt = 1;
  while (tt--) {
    run_case();
  }
  return 0;
}
