#include <bits/stdc++.h>
using namespace std;
bool sortinrev(const pair<long long, long long> &a,
               const pair<long long, long long> &b) {
  return (a.first > b.first);
}
void solve() {
  long long n, m;
  cin >> n >> m;
  long long a[n], b[m];
  for (long long i = 0; i < n; i++) cin >> a[i];
  for (long long i = 0; i < m; i++) cin >> b[i];
  long long sum = 0, max = a[0], min = b[0];
  for (long long i = 0; i < n; i++) {
    if (a[i] > max) max = a[i];
  }
  sort(a, a + n);
  for (long long i = 0; i < m; i++) {
    sum += b[i];
    if (b[i] < min) min = b[i];
  }
  sum -= b[0];
  if (max > min)
    cout << "-1";
  else if (max == min) {
    long long ans = 0;
    ans += sum;
    ans += b[0];
    for (long long i = 0; i < n - 1; i++) ans += (a[i] * m);
    cout << ans;
  } else {
    long long ans = 0;
    ans += sum;
    ans += a[n - 1];
    ans += b[0];
    ans += (a[n - 2] * (m - 1));
    for (long long i = 0; i < n - 2; i++) ans += a[i] * m;
    cout << ans;
  }
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
