#include <bits/stdc++.h>
using namespace std;
using namespace std;
int A[100000];
int B[100000];
int main() {
  int n, m;
  cin >> n >> m;
  for (int i = 0; i < n; i++) {
    cin >> A[i];
  }
  for (int i = 0; i < m; i++) {
    cin >> B[i];
  }
  if (*max_element(A, A + n) > *min_element(B, B + m)) {
    cout << -1;
  } else {
    long long ans = accumulate(A, A + n, 0LL) * m;
    sort(A, A + n);
    ans += accumulate(B, B + m, 0LL) - (long long)A[n - 1] * m;
    if (all_of(B, B + m, [&n](int k) { return k != A[n - 1]; })) {
      ans -= A[n - 2] - A[n - 1];
    }
    cout << ans;
  }
  return 0;
}
