#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
long long power(long long x, long long y, long long p) {
  long long res = 1;
  x = x % p;
  while (y > 0) {
    if (y & 1) res = (res * x) % p;
    y = y >> 1;
    x = (x * x) % p;
  }
  return res;
}
const long long L = 1e5 + 5;
long long arr[L];
long long bo[L];
long long gi[L];
long long bg[L];
priority_queue<long long> val;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long i, b, g;
  cin >> b >> g;
  long long ans = 0;
  long long x = -1e18, y = 1e18;
  for (i = 0; i < b; i++) {
    bg[i] = 1;
    cin >> bo[i];
    arr[i] = g - 1;
    ans += bo[i];
    x = max(bo[i], x);
  }
  for (i = 0; i < g; i++) {
    cin >> gi[i];
    ans += gi[i];
    val.push(gi[i]);
    y = min(gi[i], y);
  }
  if (y < x) {
    cout << -1 << endl;
    return 0;
  }
  sort(bo, bo + b);
  i = b - 1;
  while (!val.empty() && i >= 0) {
    if (val.top() >= bo[i]) {
      if (arr[i] == 0) {
        if (bo[i] == val.top()) {
          ans -= bo[i];
          val.pop();
        }
        i--;
        continue;
      }
      arr[i]--;
      val.pop();
    } else
      i--;
  }
  for (i = 0; i < b; i++) ans += arr[i] * bo[i];
  cout << ans << endl;
  return 0;
}
