#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  int b[n];
  int g[m];
  for (int i = 0; i < n; i++) cin >> b[i];
  for (int i = 0; i < m; i++) cin >> g[i];
  sort(b, b + n);
  sort(g, g + m);
  if (b[n - 1] > g[0]) {
    cout << -1;
    return 0;
  }
  long long ans = 0;
  for (int i = 0; i < m; i++) ans += g[i];
  if (g[0] != b[n - 1])
    ans += (long long)b[n - 1] + (long long)b[n - 2] * (long long)(m - 1);
  else
    ans += (long long)b[n - 2] * (long long)m;
  for (int i = 0; i < n - 2; i++) ans += (long long)m * (long long)b[i];
  cout << ans;
}
