#include <bits/stdc++.h>
using namespace std;
const int mod = 998244353;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  vector<int> a(n), b(m);
  for (int i = 0; i < n; i++) cin >> a[i];
  for (int i = 0; i < m; i++) cin >> b[i];
  sort(a.begin(), a.end());
  sort(b.begin(), b.end());
  if (a[n - 1] > b[0]) {
    cout << -1 << endl;
    return 0;
  }
  long long sum = 0LL;
  for (int i = 0; i < m; i++) sum = sum + 1LL * b[i];
  for (int i = 0; i < n - 1; i++) sum = sum + 1LL * m * a[i];
  if (n > 1 && b[0] > a[n - 1]) sum = sum + a[n - 1] - a[n - 2];
  cout << sum << endl;
}
