#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int n, m;
  cin >> n >> m;
  long long int arr_b[n];
  long long int arr_g[m];
  for (long long int i = 0; i <= (n - 1); i++) {
    cin >> arr_b[i];
  }
  for (long long int i = 0; i <= (m - 1); i++) {
    cin >> arr_g[i];
  }
  long long int ans = 0;
  for (long long int i = 0; i <= (n - 1); i++) {
    ans = ans + arr_b[i];
  }
  ans = ans * m;
  sort(arr_b, arr_b + n);
  sort(arr_g, arr_g + m);
  if (arr_g[0] < arr_b[n - 1]) {
    cout << "-1" << endl;
    return 0;
  }
  for (long long int i = (m - 1); i > 0; i--) {
    ans = ans + (arr_g[i] - arr_b[n - 1]);
  }
  if (arr_g[0] != arr_b[n - 1]) {
    ans = ans + (arr_g[0] - arr_b[n - 2]);
  }
  cout << ans << endl;
  return 0;
}
