#include <bits/stdc++.h>
using namespace std;
int mod = 1e8;
vector<long long int> a, b, pre;
int main() {
  long long int n, m;
  cin >> n >> m;
  a.resize(n + 1, 0);
  b.resize(m + 1, 0);
  pre.resize(n + 1, 0);
  long long int p = 1e10, q = -1;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
    q = max(q, a[i]);
  }
  for (int i = 1; i <= m; i++) {
    cin >> b[i];
    p = min(p, b[i]);
  }
  sort(a.begin() + 1, a.end());
  sort(b.begin() + 1, b.end());
  for (int i = 1; i <= n; i++) pre[i] = pre[i - 1] + a[i];
  if (q > p) {
    cout << -1;
    return 0;
  }
  bool flag = 0;
  long long int ans = 0;
  for (int i = 1; i <= m; i++) {
    if (i == 1 && a[n] != b[1])
      ans += pre[n] - a[n - 1] + b[i];
    else
      ans += pre[n] - a[n] + b[i];
  }
  cout << ans << endl;
  return 0;
}
