#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  vector<int> b(n), g(m);
  long long check = 0;
  for (int i = 0; i < n; i++) {
    cin >> b[i];
    check += b[i];
  }
  for (int i = 0; i < m; i++) {
    cin >> g[i];
  }
  check *= m;
  sort(b.begin(), b.end());
  sort(g.begin(), g.end());
  int maxb = b[0], ming = g[0];
  for (int i = 1; i < n; i++) {
    maxb = max(maxb, b[i]);
  }
  for (int i = 1; i < m; i++) {
    ming = min(ming, g[i]);
  }
  if (maxb > ming) {
    cout << -1;
    return 0;
  }
  for (int i = 1; i < m; i++) {
    check += g[i] - b[n - 1];
  }
  if (g[0] != b[n - 1]) {
    check += g[0] - b[n - 2];
  }
  cout << check;
}
