#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n, m;
  cin >> n >> m;
  vector<long long int> girls;
  long long int bmax, bmax2, girlsMin, data, total;
  bmax = 0;
  bmax2 = 0;
  girlsMin = 100000008;
  total = 0;
  for (int i = 0; i < n; i++) {
    cin >> data;
    total = total + data;
    if (data > bmax) {
      bmax2 = bmax;
      bmax = data;
    } else if (data > bmax2) {
      bmax2 = data;
    }
  }
  total = total * m;
  for (int i = 0; i < m; i++) {
    cin >> data;
    girls.push_back(data);
    if (data < girlsMin) girlsMin = data;
  }
  if (girlsMin < bmax) {
    printf("-1\n");
  } else {
    int flag = 0, temp = 0, flag2 = 0;
    for (int i = 0; i < m; i++) {
      if (flag == 0 && girls[i] > bmax) {
        flag = 1;
        temp = i;
      } else if ((girls[i] - bmax) == 0) {
        flag2 = -1;
      } else {
        total = total + (girls[i] - bmax);
      }
    }
    if (flag2 == -1) {
      total = total + (girls[temp] - bmax);
    } else {
      total = total + (girls[temp] - bmax2);
    }
    cout << total << "\n";
  }
  return 0;
}
