#include <bits/stdc++.h>
using namespace std;
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long n, m;
  cin >> n >> m;
  vector<long long> b(n);
  vector<long long> g(m);
  long long sum = 0;
  long long u = 0;
  for (long long i = 0; i < n; i++) {
    cin >> b[i];
    sum += b[i];
  }
  for (long long i = 0; i < m; i++) {
    cin >> g[i];
    u += g[i];
  }
  if (n == 1 || m == 1) {
    cout << -1;
    return 0;
  }
  sort(b.begin(), b.end());
  sort(g.begin(), g.end());
  if (b[n - 1] > g[0]) {
    cout << -1;
    return 0;
  }
  sum -= b[n - 1];
  sum = sum * m + u;
  if (!binary_search(g.begin(), g.end(), b[n - 1])) {
    sum += b[n - 1] - b[n - 2];
  }
  cout << sum;
  return 0;
}
