#include <bits/stdc++.h>
using namespace std;
const long long N = 1e5 + 10;
long long n, m, ans, b[N], g[N];
int32_t main() {
  cin >> n >> m;
  for (long long i = 0; i < n; i++) cin >> b[i];
  for (long long i = 0; i < m; i++) cin >> g[i];
  sort(b, b + n);
  sort(g, g + m);
  if (b[n - 1] > g[0]) return cout << -1, 0;
  long long sum = 0;
  for (long long i = 0; i < n; i++) sum += b[i];
  ans += sum * m;
  for (long long i = 1; i < m; i++) ans += max(0LL, g[i] - b[n - 1]);
  if (b[n - 1] < g[0]) ans += max(0LL, g[0] - b[n - 2]);
  cout << ans;
}
