#include <bits/stdc++.h>
using namespace std;
long long n, m, i, j, mx1, mx2, ans;
bool found = false;
int main() {
  cin >> n >> m;
  long long boys[n], girls[m];
  for (i = 0; i < n; i++) cin >> boys[i];
  for (i = 0; i < m; i++) cin >> girls[i];
  sort(boys, boys + n);
  sort(girls, girls + m);
  mx1 = boys[n - 1];
  if (mx1 > girls[0])
    cout << -1;
  else {
    mx2 = girls[m - 1];
    for (i = 0; i < m; i++) {
      if (girls[i] == mx1) {
        found = true;
        break;
      }
    }
    if (found) {
      for (i = 0; i < m; i++) ans += girls[i];
      for (i = 0; i < n - 1; i++) ans += boys[i] * m;
      cout << ans;
    } else {
      for (i = 0; i < m; i++) ans += girls[i];
      ans += mx1;
      for (i = 0; i < n - 2; i++) ans += boys[i] * m;
      ans += boys[n - 2] * (m - 1);
      cout << ans;
    }
  }
}
