#include <bits/stdc++.h>
const int INF = 0x3f3f3f3f;
const long long LLINF = 0x3f3f3f3f3f3f3f3f;
using namespace std;
long long n, m, a[300010], b[300010];
int main() {
  ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  cin >> n >> m;
  long long maxx = 0, minn = INF;
  for (long long i = 0; i < n; i++) {
    cin >> a[i];
    maxx = max(maxx, a[i]);
  }
  for (long long i = 0; i < m; i++) {
    cin >> b[i];
    minn = min(minn, b[i]);
  }
  if (maxx > minn)
    cout << "-1\n";
  else if (maxx == minn) {
    long long ans = 0;
    for (long long i = 0; i < n; i++) ans += a[i] * m;
    ans -= maxx * m;
    for (long long i = 0; i < m; i++) ans += b[i];
    cout << ans << endl;
  } else {
    long long ans = 0;
    sort(a, a + n);
    for (long long i = 0; i < n - 2; i++) ans += a[i] * m;
    ans += a[n - 2] * (m - 1) + a[n - 1];
    for (long long i = 0; i < m; i++) ans += b[i];
    cout << ans << endl;
  }
  return 0;
}
