#include <bits/stdc++.h>
using namespace std;
long long b[100005];
long long g[100005];
int main() {
  long long n, m;
  cin >> n >> m;
  long long ans = 0;
  for (long long i = 0; i < n; i++) {
    cin >> b[i];
    ans += m * b[i];
  }
  sort(b, b + n);
  for (long long i = 0; i < m; i++) {
    cin >> g[i];
  }
  sort(g, g + m);
  for (int i = 1; i < m; i++) ans += g[i] - b[n - 1];
  if (b[n - 1] > g[0] or (n == 1 and g[0] != b[n - 1])) {
    cout << -1;
    return 0;
  }
  if (n == 1)
    cout << ans;
  else {
    if (g[0] != b[n - 1]) ans += g[0] - b[n - 2];
    cout << ans;
  }
}
