#include <bits/stdc++.h>
using namespace std;
template <typename T>
inline bool chmax(T& a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <typename T>
inline bool chmin(T& a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
const double EPS = 1e-10;
const double PI = acos(-1);
struct safe_hash {
  static uint64_t splitmix64(uint64_t x) {
    x += 0x9e3779b97f4a7c15;
    x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
    x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
    return x ^ (x >> 31);
  }
  size_t operator()(uint64_t x) const {
    static const uint64_t FIXED_RANDOM =
        chrono::steady_clock::now().time_since_epoch().count();
    return splitmix64(x + FIXED_RANDOM);
  }
};
using hash_set = unordered_set<long long, safe_hash>;
using hash_multiset = unordered_set<long long, safe_hash>;
template <typename T>
using hash_map = unordered_map<long long, T, safe_hash>;
template <typename T>
using hash_multimap = unordered_map<long long, T, safe_hash>;
class AThePartyAndSweets {
 public:
  void solve(std::istream& in, std::ostream& out) {
    ios_base::sync_with_stdio(false);
    in.tie(nullptr), out.tie(nullptr);
    int N, M;
    in >> N >> M;
    vector<long long> A(N), B(M);
    for (int i = (0); i < (N); ++i) in >> A[i];
    for (int i = (0); i < (M); ++i) in >> B[i];
    long long mx = *max_element((A).begin(), (A).end()),
              mn = *min_element((B).begin(), (B).end());
    if (mn < mx) {
      out << "-1\n";
      return;
    }
    long long ans = M * accumulate((A).begin(), (A).end(), 0LL);
    for (int i = (0); i < (M); ++i) ans += B[i] - mx;
    if (mx < mn) {
      sort((A).rbegin(), (A).rend());
      ans += A[0] - A[1];
    }
    out << ans << '\n';
  }
};
int main() {
  AThePartyAndSweets solver;
  std::istream& in(std::cin);
  std::ostream& out(std::cout);
  solver.solve(in, out);
  return 0;
}
