#include <bits/stdc++.h>
using namespace std;
int n, m;
long long sum = 0, b[100000], g[100000], ans;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> m;
  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];
  sort(b, b + n);
  sort(g, g + m);
  ans = sum * m;
  int cnt = 0;
  for (long long i = (0); i < (m - 1); ++i) {
    if (g[i] < b[n - 1]) {
      cout << -1 << endl;
      return 0;
    }
    if (g[i] > b[n - 1]) {
      ans += g[i] - b[n - 1];
      cnt++;
    }
  }
  int j = m - 1;
  if (g[j] < b[n - 1]) {
    cout << -1 << endl;
    return 0;
  } else if (g[j] > b[n - 1])
    ans += g[j] - b[n - 1 - (cnt == m - 1)];
  cout << ans << endl;
  return 0;
}
