#include <bits/stdc++.h>
using namespace std;
const long long int mod = 1e9 + 7;
const long long int N = 100005;
const long long int MAX = 1e6 + 3;
long long int modPow(long long int a, long long int b) {
  long long int res = 1;
  a %= mod;
  for (; b; b >>= 1) {
    if (b & 1) res = res * a % mod;
    a = a * a % mod;
  }
  return res;
}
long long int nCr(long long int n, long long int k) {
  long long int res = 1;
  if (n < k) return 0;
  if (k > n - k) k = n - k;
  for (long long int i = 0; i < k; ++i) {
    res = (res * (n - i)) % mod;
    res = (res * modPow(i + 1, mod - 2)) % mod;
  }
  return res;
}
void Sieve() {
  set<int> s;
  bool prime[1000009];
  memset(prime, true, sizeof(prime));
  for (long long int p = 2; p * p <= 1000006; p++)
    if (prime[p] == true)
      for (long long int i = p * 2; i <= 1000006; i += p) prime[i] = false;
  for (long long int i = 2; i < 1000006; i++)
    if (prime[i] == true) s.insert(i);
}
long long int factorial(long long int n) {
  if (n == 1) return 1;
  return (n * factorial(n - 1)) % mod;
}
long long int catalan(long long int n) {
  return (nCr(2 * n, n) * modPow(n + 1, mod - 2)) % mod;
}
string to_str(long long int num) {
  if (num == 0) return "0";
  string str;
  while (num) {
    str += char(num % 10 + '0');
    num /= 10;
  }
  reverse(str.begin(), str.end());
  return str;
}
int main() {
  int n, m;
  cin >> n >> m;
  int a[n], b[m];
  int ma = -1, mi = INT_MAX;
  long long int suma = 0;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    ma = max(ma, a[i]);
    suma += a[i];
  }
  suma -= ma;
  sort(a, a + n, greater<int>());
  long long int ans = 0;
  for (int i = 0; i < m; i++) {
    cin >> b[i];
    mi = min(mi, b[i]);
    if (b[i] < ma) return cout << -1, 0;
    ans += b[i] + suma;
  }
  if (ma == mi)
    cout << ans;
  else
    cout << ans + ma - a[1];
}
