#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long N, M;
  cin >> N >> M;
  vector<long long> b;
  vector<long long> g;
  long long inp;
  for (long long i = 0; i < N; i++) {
    cin >> inp;
    b.push_back(inp);
  }
  sort(b.begin(), b.end());
  long long gsum = 0;
  for (long long i = 0; i < M; i++) {
    cin >> inp;
    g.push_back(inp);
    gsum = gsum + inp;
  }
  sort(g.begin(), g.end());
  long long ans = gsum - g[0];
  if (b[N - 1] > g[0]) {
    cout << -1 << endl;
    return 0;
  } else {
    long long st = 0;
    if (b[N - 1] == g[0]) {
      st = 1;
    }
    ans = ans + b[N - 1];
    if (st == 1) {
      ans = ans + b[N - 2] * M;
    } else {
      ans = ans + b[N - 2] * (M - 1) + g[0];
    }
    for (long long i = N - 3; i >= 0; i = i - 1) {
      ans = ans + b[i] * M;
    }
    cout << ans << endl;
  }
}
