#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, m;
  cin >> n >> m;
  long long b[n];
  long long g[m];
  for (int i = 0; i < n; i++) cin >> b[i];
  for (int i = 0; i < m; i++) cin >> g[i];
  sort(b, b + n);
  sort(g, g + m);
  if (b[n - 1] > g[0]) {
    cout << -1 << endl;
    return 0;
  }
  long long sum = 0;
  for (int i = 0; i < n - 1; i++) {
    sum += b[i];
  }
  sum *= (m);
  long long sum2 = 0;
  for (int i = 0; i < m; i++) sum2 += g[i];
  long long answer;
  if (g[0] == b[n - 1])
    answer = sum2 + sum;
  else {
    answer = sum + g[0] - b[n - 2] + sum2 - g[0] + b[n - 1];
  }
  cout << answer << endl;
}
