#include <bits/stdc++.h>
using namespace std;
long long modexp(long long n, long long m) {
  if (m == 0)
    return 1;
  else if (m == 1)
    return n;
  else {
    long long p = modexp(n, m / 2);
    if (m % 2 == 1)
      return (((p * p) % 1000000007) * n) % 1000000007;
    else
      return (p * p) % 1000000007;
  }
}
long long exp(long long n, long long m) {
  if (m == 0) return 1;
  if (m == 1) return n;
  long long p = exp(n, m / 2);
  if (m % 2 == 1)
    return p * p * n;
  else
    return p * p;
}
long long gcd(long long a, long long b) {
  if (a == 0) return b;
  return gcd(b % a, a);
}
long long inv(long long n) { return exp(n, 1000000007 - 2); }
long long lcm(long long a, long long b) { return a * b / gcd(a, b); }
long long factorial(long long fact[], long long n) {
  fact[0] = 1;
  fact[1] = 1;
  long long prod = 1, i;
  for (i = 2; i < n + 1; i++) {
    prod = (prod * i) % 1000000007;
    fact[i] = prod;
  }
  return prod;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long n, i, j, k, m, q, t;
  cin >> n >> m;
  vector<long long> b(n), g(m);
  for (i = 0; i < n; i++) cin >> b[i];
  for (i = 0; i < m; i++) cin >> g[i];
  sort(b.begin(), b.end());
  sort(g.begin(), g.end());
  long long cost = 0;
  if (b[n - 1] > g[0])
    cout << -1;
  else {
    for (i = 0; i < m; i++) cost += g[i];
    if (b[n - 1] == g[0]) {
      for (i = 0; i < n - 1; i++) cost += m * b[i];
      cout << cost << endl;
    } else {
      for (i = 0; i < n - 2; i++) cost += m * b[i];
      cost += (m - 1) * b[i];
      i++;
      cost += b[i];
      cout << cost << endl;
    }
  }
  return 0;
}
