#include <bits/stdc++.h>
using namespace std;
int n, m;
int a[100005];
int b[100005];
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> m;
  long long int ans = 0;
  for (int i = 1; i <= n; i++) cin >> a[i], ans += a[i] * 1ll * m;
  for (int i = 1; i <= m; i++) cin >> b[i];
  sort(a + 1, a + n + 1);
  sort(b + 1, b + m + 1);
  if (b[1] < a[n]) return cout << -1 << '\n', 0;
  for (int i = 2; i <= m; i++) ans = ans + b[i] - a[n];
  if (b[1] != a[n]) ans += b[1] - a[n - 1];
  cout << ans << '\n';
  return 0;
}
