#include <bits/stdc++.h>
using namespace std;
const int N = 3e5 + 5;
int b[N], g[N];
int main() {
  ios::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL);
  int n, m;
  cin >> n >> m;
  long long ans = 0;
  for (int i = 0; i < int(n); i++) {
    cin >> b[i];
    ans += b[i];
  }
  long long g_min = 2e10;
  for (int j = 0; j < int(m); j++) {
    cin >> g[j];
    g_min = min(g_min, g[j] + 0LL);
  }
  sort(b, b + n);
  if (b[n - 1] > g_min) {
    cout << "-1" << '\n';
    return 0;
  }
  ans = ans * m;
  int cnt = 0;
  for (int j = 0; j < int(m); j++) {
    if (g[j] == b[n - 1]) continue;
    cnt++;
    ans += abs(b[n - 1] - g[j] + 0LL);
  }
  if (cnt == m) ans += b[n - 1] - b[n - 2];
  cout << ans << '\n';
  return 0;
}
