#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n, m;
  cin >> n >> m;
  vector<int> b(n);
  for (int i = 0; i < n; i++) {
    cin >> b[i];
  }
  vector<int> g(m);
  for (int i = 0; i < m; i++) {
    cin >> g[i];
  }
  sort(b.rbegin(), b.rend());
  sort(g.rbegin(), g.rend());
  long long ans = 0;
  if (b.front() > g.back()) {
    ans = -1;
  } else if (b.front() == g.back()) {
    ans = (accumulate(b.begin(), b.end(), 0ll) * 1ll * m) +
          accumulate(g.begin(), g.end(), 0ll) - (b.front() * 1ll * m);
  } else {
    ans = (accumulate(b.begin(), b.end(), 0ll) * 1ll * m) +
          accumulate(g.begin(), g.end(), 0ll) - (b.front() * 1ll * (m - 1)) -
          b[1];
  }
  cout << ans << '\n';
  return 0;
}
