#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, m, g[100005], b[100005], i, j, bmax, bmax2, gmin, ans = 0;
  cin >> n >> m;
  for (i = 0; i < n; i++) cin >> b[i];
  for (i = 0; i < m; i++) cin >> g[i];
  bmax = 0;
  for (i = 1; i < n; i++)
    if (b[i] > b[bmax]) bmax = i;
  gmin = 0;
  for (i = 1; i < m; i++)
    if (g[i] < g[gmin]) gmin = i;
  if (g[gmin] < b[bmax]) {
    cout << "-1";
    return 0;
  }
  for (i = 0; i < n; i++) {
    if (i != bmax)
      ans += b[i] * m;
    else {
      for (j = 0; j < m; j++) ans += g[j];
    }
  }
  if (b[bmax] != g[gmin]) {
    if (bmax == 0)
      bmax2 = 1;
    else
      bmax2 = 0;
    for (i = 0; i < n; i++)
      if (i != bmax && b[bmax2] < b[i]) bmax2 = i;
    ans += b[bmax] - b[bmax2];
  }
  cout << ans;
}
