#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.precision(20);
  int n, m;
  cin >> n >> m;
  long long int a[n], b[m], mx, mn = INT_MAX, s1 = 0, s2 = 0;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    s1 += a[i];
  }
  sort(a, a + n);
  mx = a[n - 1];
  for (int i = 0; i < m; i++) {
    cin >> b[i];
    mn = min(mn, b[i]);
    s2 += b[i];
  }
  if (mx > mn)
    cout << -1;
  else if (mx == mn)
    cout << s1 * m + s2 - mx * m;
  else
    cout << s1 * m + s2 - mx * (m - 1) - a[n - 2];
  return 0;
}
