#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
void _print(long long t) { cerr << t; }
void _print(string t) { cerr << t; }
void _print(char t) { cerr << t; }
void _print(long double t) { cerr << t; }
void _print(bool t) { cerr << t; }
template <class T, class V>
void _print(pair<T, V> p);
template <class T>
void _print(vector<T> v);
template <class T>
void _print(set<T> v);
template <class T, class V>
void _print(map<T, V> v);
template <class T>
void _print(multiset<T> v);
template <class T, class V>
void _print(pair<T, V> p) {
  cerr << "{";
  _print(p.first);
  cerr << ",";
  _print(p.second);
  cerr << "}";
}
template <class T>
void _print(vector<T> v) {
  cerr << "[";
  for (T i : v) {
    _print(i);
    cerr << " ";
  }
  cerr << "]";
}
template <class T>
void _print(set<T> v) {
  cerr << "[ ";
  for (T i : v) {
    _print(i);
    cerr << " ";
  }
  cerr << "]";
}
template <class T>
void _print(multiset<T> v) {
  cerr << "[ ";
  for (T i : v) {
    _print(i);
    cerr << " ";
  }
  cerr << "]";
}
template <class T, class V>
void _print(map<T, V> v) {
  cerr << "[ ";
  for (auto i : v) {
    _print(i);
    cerr << " ";
  }
  cerr << "]";
}
void solve() {
  long long n, m, sumg = 0;
  cin >> n >> m;
  vector<long long> b(n), g(m);
  for (long long i = 0; i <= n - 1; i++) {
    cin >> b[i];
  }
  for (long long i = 0; i <= m - 1; i++) {
    cin >> g[i];
    sumg += g[i];
  }
  sort((b).begin(), (b).end());
  sort((g).begin(), (g).end());
  if (g[0] < b[n - 1]) {
    cout << "-1\n";
    return;
  }
  long long ans = 0;
  if (g[0] == b[n - 1]) {
    ans += sumg;
    for (long long i = 0; i <= n - 2; i++) {
      ans += (b[i] * m);
    }
  } else {
    ans += sumg;
    for (long long i = 0; i <= n - 1; i++) {
      if (i == n - 1) {
        ans += (b[i]);
      } else if (i == n - 2) {
        ans += b[i] * (m - 1);
      } else {
        ans += (b[i] * m);
      }
    }
  }
  cout << ans << "\n";
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long t = 1;
  for (long long i = 1; i <= t; i++) {
    solve();
  }
  return 0;
}
