#include <bits/stdc++.h>
using namespace std;
long long N, M;
vector<long long> A, B;
int main() {
  cin >> N >> M;
  long long a, b;
  for (int i = 1; i <= N; i++) {
    cin >> a;
    A.push_back(a);
  }
  for (int i = 1; i <= M; i++) {
    cin >> b;
    B.push_back(b);
  }
  sort(A.begin(), A.end(), greater<long long>());
  sort(B.begin(), B.end(), greater<long long>());
  if (A[0] > B[M - 1]) {
    cout << -1 << endl;
    return 0;
  }
  long long ans = 0;
  for (int i = 0; i < M; i++) ans += B[i];
  if (A[0] != B[M - 1]) ans += A[0];
  if (A[0] != B[M - 1])
    ans += A[1] * (M - 1);
  else
    ans += A[1] * M;
  for (int i = 2; i < N; i++) ans += M * A[i];
  cout << ans << endl;
}
