#include <bits/stdc++.h>
using namespace std;
long long n, m;
long long b[100005], g[100005];
long long sum = 0;
bool chk = 0;
void input() {
  cin >> n >> m;
  for (long long i = 1; i <= n; i++) {
    cin >> b[i];
  }
  for (long long i = 1; i <= m; i++) {
    cin >> g[i];
  }
  return;
}
void solve() {
  sort(b + 1, b + n + 1);
  sort(g + 1, g + m + 1);
  for (long long i = m; i >= 1; i--) {
    if (b[n] > g[i]) {
      sum = -1;
      return;
    }
    if (i == 1) {
      if (b[n] == g[1]) {
        sum += g[1];
        chk = 1;
      } else {
        sum += b[n];
      }
      break;
    }
    sum += g[i];
  }
  if (chk) {
    sum += m * b[n - 1];
  } else {
    sum += (m - 1) * b[n - 1] + g[1];
  }
  for (long long i = n - 2; i >= 1; i--) {
    sum += m * b[i];
  }
  return;
}
void output() {
  cout << sum;
  return;
}
signed main() {
  ios_base::sync_with_stdio(false);
  input();
  solve();
  output();
  return 0;
}
