#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  long long n, m;
  cin >> n >> m;
  long long boys = 0, girls = 0;
  long long b1 = 0, b2 = 0;
  for (int i = 0; i < n; i++) {
    int a;
    cin >> a;
    boys += a;
    if (a > b1) {
      b2 = b1;
      b1 = a;
    } else if (a > b2)
      b2 = a;
  }
  long long g;
  cin >> g;
  girls += g;
  for (int i = 1; i < m; i++) {
    long long a;
    cin >> a;
    girls += a;
    g = min(g, a);
  }
  if (b1 > g) {
    cout << "-1\n";
    return 0;
  }
  if (b1 == g) {
    cout << boys * m + girls - b1 * m << '\n';
  } else
    cout << boys * m + girls - b1 * (m - 1) - b2 << '\n';
  return 0;
}
