#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  long long n, m;
  cin >> n >> m;
  vector<long long> B(n), G(m);
  for (long long &x : B) cin >> x;
  for (long long &x : G) cin >> x;
  sort(B.begin(), B.end());
  sort(G.begin(), G.end());
  if (B.back() > G[0]) {
    cout << -1 << "\n";
    return 0;
  }
  long long ans = 0;
  for (int i = 0; i < n; i++) ans += B[i] * m;
  if (B.back() < G[0]) ans += G[0] - B[n - 2];
  for (int i = 1; i < m; i++) ans += G[i] - B.back();
  cout << ans << "\n";
  return 0;
}
