#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:512000000")
using namespace std;
void solve(__attribute__((unused)) bool);
void precalc();
clock_t start;
int main() {
  start = clock();
  int t = 1;
  cout.sync_with_stdio(0);
  cin.tie(0);
  precalc();
  cout.precision(10);
  cout << fixed;
  int testNum = 1;
  while (t--) {
    solve(true);
  }
  cout.flush();
  return 0;
}
template <typename T>
T binpow(T q, T w, T mod) {
  if (!w) return 1 % mod;
  if (w & 1) return q * 1LL * binpow(q, w - 1, mod) % mod;
  return binpow(q * 1LL * q % mod, w / 2, mod);
}
template <typename T>
T gcd(T q, T w) {
  while (w) {
    q %= w;
    swap(q, w);
  }
  return q;
}
template <typename T>
T lcm(T q, T w) {
  return q / gcd(q, w) * w;
}
template <typename T>
void make_unique(vector<T>& a) {
  sort(a.begin(), a.end());
  a.erase(unique(a.begin(), a.end()), a.end());
}
template <typename T>
void relax_min(T& cur, T val) {
  cur = min(cur, val);
}
template <typename T>
void relax_max(T& cur, T val) {
  cur = max(cur, val);
}
void precalc() {}
void solve(__attribute__((unused)) bool read) {
  long long n, m;
  cin >> n >> m;
  vector<long long> b(n);
  for (long long i = 0; i < n; ++i) {
    cin >> b[i];
  }
  sort(b.begin(), b.end());
  vector<long long> g(m);
  for (long long i = 0; i < m; ++i) {
    cin >> g[i];
  }
  sort(g.begin(), g.end());
  if (b.back() > g[0]) {
    cout << "-1\n";
    return;
  }
  long long ans = 0;
  for (long long i = 0; i < n; ++i) {
    ans += b[i] * m;
  }
  for (long long i = m - 1; i >= 0; --i) {
    if (g[i] > b.back()) {
      ans += g[i] - b.back();
      if (i == 0) {
        ans += b[n - 1] - b[n - 2];
      }
    }
  }
  cout << ans << endl;
}
