#include <bits/stdc++.h>
const long long N = 500005;
const long long mod = 1e9 + 7;
using namespace std;
void solve() {
  long long n, x = 0, y = 0, k, m, ans = 1e15, c = 0;
  cin >> n >> m;
  long long a[n], b[m];
  for (long long i = 0; i < n; ++i) {
    cin >> a[i];
  }
  for (long long i = 0; i < m; ++i) {
    cin >> b[i];
  }
  sort(a, a + n);
  sort(b, b + m);
  if (a[n - 1] > b[0]) {
    cout << -1 << "\n";
    return;
  }
  for (long long i = 0; i < n - 1; ++i) {
    x += a[i];
  }
  c += b[m - 1];
  if (b[0] == a[n - 1])
    c += a[n - 1];
  else
    c = c + b[0] + a[n - 1];
  for (long long i = 1; i < m - 1; ++i) {
    c += b[i];
  }
  c += m * x;
  if (b[0] != a[n - 1]) c -= a[n - 2];
  cout << c << "\n";
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long T = 1;
  while (T--) {
    solve();
  }
  return 0;
}
