#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9 + 5;
const int MXN = 1e5 + 5;
long long n, m, girls[MXN], boys[MXN], maxb, maxg, sumb = 0, sumg = 0;
int main() {
  {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cout << fixed << setprecision(10);
    cerr << fixed << setprecision(10);
  };
  cin >> n >> m;
  for (int i = 0; i < n; i++) {
    cin >> boys[i];
    sumb += boys[i];
  }
  for (int i = 0; i < m; i++) {
    cin >> girls[i];
    sumg += girls[i];
  }
  maxb = *max_element(boys, boys + n);
  maxg = *min_element(girls, girls + m);
  sort(boys, boys + n);
  if (maxb > maxg) {
    return cout << -1 << '\n', 0;
  }
  if (maxb == maxg) {
    cout << sumb * m + sumg - maxb * m << '\n';
  } else {
    cout << sumb * m + sumg - maxb * (m - 1) - boys[n - 2];
  }
  return 0;
}
