#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long n, m, i, j, sw = 0, nsw;
  bool presMin;
  cin >> n >> m;
  vector<long long> b(n), g(m);
  for (i = 0; i < n; i++) cin >> b[i];
  for (i = 0; i < m; i++) cin >> g[i];
  sort(b.rbegin(), b.rend());
  sort(g.begin(), g.end());
  if (b[0] <= g[0]) {
    j = 0;
    for (i = 0; i < n; i++) {
      nsw = m;
      presMin = false;
      while ((nsw > 1 or (presMin and nsw > 0)) and j < m) {
        nsw--;
        if (g[j] == b[i]) presMin = true;
        sw += g[j++];
      }
      sw += b[i] * nsw;
    }
    cout << sw << endl;
  } else
    cout << -1 << endl;
  return 0;
}
