#include <bits/stdc++.h>
using namespace std;
int main() {
  long long m, n;
  cin >> n >> m;
  vector<long long> g(m), b(n);
  long long sum = 0;
  for (int i = 0; i < n; i++) {
    cin >> b[i];
  }
  for (int i = 0; i < m; i++) {
    cin >> g[i];
    sum += g[i];
  }
  sort(b.begin(), b.end());
  sort(g.begin(), g.end());
  long long ans = 0;
  if (g[0] < b[n - 1]) {
    ans = -1;
  } else {
    for (int i = 0; i < n - 2; i++) {
      ans += (m * b[i]);
    }
    if (g[0] > b[n - 1])
      ans += ((m - 1) * b[n - 2] + b[n - 1] + sum);
    else
      ans += sum + b[n - 2] * m;
  }
  cout << ans << endl;
}
