#include <bits/stdc++.h>
using namespace std;
long long int power(long long int a, long long int b, long long int m) {
  if (b == 0) return (1);
  long long int sol = power(a, b / 2, m);
  sol = (sol * sol) % m;
  if (b % 2 == 1) sol = (sol * a) % m;
  return (sol);
}
long long int gcd(long long int a, long long int b) {
  if (a % b == 0)
    return b;
  else {
    return gcd(b, a % b);
  }
}
long long int a[100005], b[100005], vis[100005];
void solve() {
  long long int sol = 0;
  long long int n, m;
  cin >> n >> m;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    sol = sol + a[i] * m;
  }
  for (int i = 0; i < m; i++) {
    cin >> b[i];
  }
  sort(a, a + n);
  sort(b, b + m);
  if (b[0] < a[n - 1]) {
    cout << "-1";
    return;
  }
  for (int i = 1; i < m; i++) {
    sol = sol + b[i] - a[n - 1];
  }
  if (b[0] != a[n - 1]) sol = sol + b[0] - a[n - 2];
  cout << sol;
}
int main() {
  int t = 1;
  while (t--) solve();
  return (0);
}
