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