#include <bits/stdc++.h>
using namespace std;
long long int input(long long int n);
long long int max_of_all();
vector<long long int> v;
long long int input(long long int n) {
  long long int val;
  for (long long int i = 0; i < n; i++) {
    cin >> val;
    v.push_back(val);
  }
  return 0;
}
long long int max_of_all(vector<long long int> &vec) {
  auto itr = max_element(vec.begin(), vec.end());
  return *itr;
}
int main(void) {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long int n, m, a;
  long long int ans = 0;
  cin >> n >> m;
  long long int min = 1000000000, max = -1;
  vector<long long int> b, g;
  for (int i = 0; i < n; i++) {
    cin >> a;
    b.push_back(a);
    if (a > max) {
      max = a;
    }
    ans += a;
  }
  ans *= m;
  sort(b.begin(), b.end());
  long long int x = b[n - 1];
  for (int i = 0; i < m; i++) {
    cin >> a;
    g.push_back(a);
    if (a < min) {
      min = a;
    }
  }
  sort(g.begin(), g.end());
  if (min < max) {
    cout << "-1" << endl;
    return 0;
  }
  for (int i = m - 1; i >= 1; i--) {
    ans += g[i] - x;
  }
  if (g[0] - x != 0) {
    ans += -b[n - 2] + g[0];
  }
  cout << ans << endl;
  return 0;
}
