#include <iostream>
#include <sstream>
#include <iomanip>
#include <vector>
#include <string>
#include <map>
#include <set>
#include <algorithm>
#include <numeric>
#include <iterator>
#include <functional>
#include <complex>
#include <queue>
#include <stack>
#include <cmath>
#include <cassert>
using namespace std;
typedef long long LL;
typedef long double LD;
typedef complex<double> CMP;

static const int INF = 999, UNK = -1;

int bitcnt(int x)
{
	int c = 0;
	for(; x; x>>=1)
		c += x&1;
	return c;
}

class AntlerSwapping { public:
	int getmin(vector <int> a, vector <int> b, int capacity)
	{
		int N = a.size();
		vector<bool> tbl(1<<N);
		for(int mask=1; mask<(1<<N); ++mask)
		{
			vector<int> c;
			for(int i=0; (1<<i)<=mask; ++i)
				if((1<<i) & mask) {
					c.push_back(a[i]);
					c.push_back(b[i]);
				}
			sort(c.begin(), c.end());
			bool can = true;
			for(int i=0; i+1<c.size(); i+=2)
				if(abs(c[i]-c[i+1]) > capacity)
					can = false;
			tbl[mask] = can;
		}
		vector<int> memo(1<<N, UNK);
		int best = rec((1<<N)-1, tbl, memo);
		return best>=INF ? -1 : best;
	}

	int rec(int mask, const vector<bool>& tbl, vector<int>& memo)
	{
		if(memo[mask] != UNK)
			return memo[mask];
		if(mask == 0)
			return 0;
		int best = INF;
		for(int m2=mask; m2; m2=(m2-1)&mask)
		{
			int bc = bitcnt(m2);
			if(tbl[m2])
				best = min(best, (bc-1) + rec(mask&~m2, tbl, memo));
		}
		return memo[mask] = best;
	}
};

// BEGIN CUT HERE
#include <ctime>
double start_time; string timer()
 { ostringstream os; os << " (" << int((clock()-start_time)/CLOCKS_PER_SEC*1000) << " msec)"; return os.str(); }
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v)
 { os << "{ ";
   for(typename vector<T>::const_iterator it=v.begin(); it!=v.end(); ++it)
   os << '\"' << *it << '\"' << (it+1==v.end() ? "" : ", "); os << " }"; return os; }
void verify_case(const int& Expected, const int& Received) {
 bool ok = (Expected == Received);
 if(ok) cerr << "PASSED" << timer() << endl;  else { cerr << "FAILED" << timer() << endl;
 cerr << "\to: \"" << Expected << '\"' << endl << "\tx: \"" << Received << '\"' << endl; } }
#define CASE(N) {cerr << "Test Case #" << N << "..." << flush; start_time=clock();
#define END	 verify_case(_, AntlerSwapping().getmin(antler1, antler2, capacity));}
int main(){

CASE(0)
	int antler1_[] = {3, 2, 2};
	  vector <int> antler1(antler1_, antler1_+sizeof(antler1_)/sizeof(*antler1_)); 
	int antler2_[] = {3, 5, 5};
	  vector <int> antler2(antler2_, antler2_+sizeof(antler2_)/sizeof(*antler2_)); 
	int capacity = 0; 
	int _ = 1; 
END
CASE(1)
	int antler1_[] = {4, 2, 6, 4, 8, 5, 2, 3};
	  vector <int> antler1(antler1_, antler1_+sizeof(antler1_)/sizeof(*antler1_)); 
	int antler2_[] = {3, 4, 5, 2, 8, 5, 7, 6};
	  vector <int> antler2(antler2_, antler2_+sizeof(antler2_)/sizeof(*antler2_)); 
	int capacity = 1; 
	int _ = 2; 
END
CASE(2)
	int antler1_[] = {12, 34, 56, 78};
	  vector <int> antler1(antler1_, antler1_+sizeof(antler1_)/sizeof(*antler1_)); 
	int antler2_[] = {1234, 2345, 3456, 4567};
	  vector <int> antler2(antler2_, antler2_+sizeof(antler2_)/sizeof(*antler2_)); 
	int capacity = 100; 
	int _ = -1; 
END
CASE(3)
	int antler1_[] = {47, 58, 2013};
	  vector <int> antler1(antler1_, antler1_+sizeof(antler1_)/sizeof(*antler1_)); 
	int antler2_[] = {49, 55, 2013};
	  vector <int> antler2(antler2_, antler2_+sizeof(antler2_)/sizeof(*antler2_)); 
	int capacity = 3; 
	int _ = 0; 
END
CASE(4)
	int antler1_[] = {4, 1, 7, 5, 7, 8, 2, 1, 3, 1, 7, 5, 9, 4, 9, 1};
	  vector <int> antler1(antler1_, antler1_+sizeof(antler1_)/sizeof(*antler1_)); 
	int antler2_[] = {10, 6, 5, 3, 1, 8, 4, 4, 4, 7, 1, 4, 6, 5, 10, 10};
	  vector <int> antler2(antler2_, antler2_+sizeof(antler2_)/sizeof(*antler2_)); 
	int capacity = 1; 
	int _ = 7; 
END
/*
CASE(5)
	int antler1_[] = ;
	  vector <int> antler1(antler1_, antler1_+sizeof(antler1_)/sizeof(*antler1_)); 
	int antler2_[] = ;
	  vector <int> antler2(antler2_, antler2_+sizeof(antler2_)/sizeof(*antler2_)); 
	int capacity = ; 
	int _ = ; 
END
CASE(6)
	int antler1_[] = ;
	  vector <int> antler1(antler1_, antler1_+sizeof(antler1_)/sizeof(*antler1_)); 
	int antler2_[] = ;
	  vector <int> antler2(antler2_, antler2_+sizeof(antler2_)/sizeof(*antler2_)); 
	int capacity = ; 
	int _ = ; 
END
*/
}
// END CUT HERE
