#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long n, m;
  cin >> n >> m;
  long long ar[n], br[m];
  long long sum1 = 0;
  for (long long i = 0; i < n; i++) {
    cin >> ar[i];
    sum1 = sum1 + ar[i];
  }
  long long sum2 = 0;
  for (long long i = 0; i < m; i++) {
    cin >> br[i];
    sum2 = sum2 + br[i];
  }
  sort(ar, ar + n);
  sort(br, br + m);
  if (ar[n - 1] > br[0])
    cout << -1;
  else {
    if (ar[n - 1] == br[0]) {
      long long sum = sum2 + (sum1 - ar[n - 1]) * m;
      cout << sum;
    } else {
      long long sum = sum2 - br[0] + ar[n - 1] + br[0] + (m - 1) * ar[n - 2] +
                      m * (sum1 - ar[n - 1] - ar[n - 2]);
      cout << sum;
    }
  }
  return 0;
}
