#include <bits/stdc++.h>
using namespace std;
/*
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
*/
#define int long long
#define REP(i,n) for(int i = 0;i < (int)(n);i++)
#define RREP(i,n) for(int i = (int)n-1;i >= 0;i--)
#define FOR(i,s,n) for(int i = s;i < (int)n;i++)
#define RFOR(i,s,n) for(int i = (int)n-1;i >= s;i--)
#define ALL(a) a.begin(),a.end()
#define IN(a, x, b) (a<=x && x<b)
template<class T>inline bool CHMAX(T&a,T b){if(a<b){a = b;return true;}return false;}
template<class T>inline bool CHMIN(T&a,T b){if(a>b){a = b;return true;}return false;}
template<class T>istream&operator >>(istream&is,vector<T>&vec){for(T&x:vec)is>>x;return is;}
template<class T>inline void in(T&t){cin>>t;}
template<class T,class... Ts>inline void in(T&t,Ts&...ts){cin>>t;in(ts...);}
template<class T>inline void out(T t){cout<<t<<endl;}
template<class T,class... Ts>inline void out(T t,Ts... ts){cout<<t<<" ";out(ts...);}
template<typename T=int>vector<T>mv(size_t a){return vector<T>(a);}
template<typename T=int,typename... Ts>auto mv(size_t a,Ts... ts){return vector<decltype(mv<T>(ts...))>(a,mv<T>(ts...));}
template<typename T,typename V>typename enable_if<is_class<T>::value==0>::type fill(T&t,const V&v){t=v;}
template<typename T,typename V>typename enable_if<is_class<T>::value!=0>::type fill(T&t,const V&v){for(auto &e:t)fill(e,v);}
constexpr long long INF = 1e18;

template<int MOD> struct Fp {
	long long val;
	constexpr Fp(long long v = 0) noexcept : val(v % MOD) {
		if (val < 0) val += MOD;
	}
	constexpr int getmod() { return MOD; }
	constexpr Fp operator - () const noexcept {
		return val ? MOD - val : 0;
	}
	constexpr Fp operator + (const Fp& r) const noexcept { return Fp(*this) += r; }
	constexpr Fp operator - (const Fp& r) const noexcept { return Fp(*this) -= r; }
	constexpr Fp operator * (const Fp& r) const noexcept { return Fp(*this) *= r; }
	constexpr Fp operator / (const Fp& r) const noexcept { return Fp(*this) /= r; }
	constexpr Fp& operator += (const Fp& r) noexcept {
		val += r.val;
		if (val >= MOD) val -= MOD;
		return *this;
	}
	constexpr Fp& operator -= (const Fp& r) noexcept {
		val -= r.val;
		if (val < 0) val += MOD;
		return *this;
	}
	constexpr Fp& operator *= (const Fp& r) noexcept {
		val = val * r.val % MOD;
		return *this;
	}
	constexpr Fp& operator /= (const Fp& r) noexcept {
		long long a = r.val, b = MOD, u = 1, v = 0;
		while (b) {
			long long t = a / b;
			a -= t * b; swap(a, b);
			u -= t * v; swap(u, v);
		}
		val = val * u % MOD;
		if (val < 0) val += MOD;
		return *this;
	}
	constexpr bool operator == (const Fp& r) const noexcept {
		return this->val == r.val;
	}
	constexpr bool operator != (const Fp& r) const noexcept {
		return this->val != r.val;
	}
	friend constexpr ostream& operator << (ostream &os, const Fp<MOD>& x) noexcept {
		return os << x.val;
	}
	friend constexpr Fp<MOD> modpow(const Fp<MOD> &a, long long n) noexcept {
		if (n == 0) return 1;
		auto t = modpow(a, n / 2);
		t = t * t;
		if (n & 1) t = t * a;
		return t;
	}
};
 
// 二項係数ライブラリ
template<class T> struct BiCoef {
	vector<T> fact_, inv_, finv_;
	constexpr BiCoef() {}
	constexpr BiCoef(int n) noexcept : fact_(n, 1), inv_(n, 1), finv_(n, 1) {
		init(n);
	}
	constexpr void init(int n) noexcept {
		fact_.assign(n, 1), inv_.assign(n, 1), finv_.assign(n, 1);
		int MOD = fact_[0].getmod();
		for(int i = 2; i < n; i++){
			fact_[i] = fact_[i-1] * i;
			inv_[i] = -inv_[MOD%i] * (MOD/i);
			finv_[i] = finv_[i-1] * inv_[i];
		}
	}
	constexpr T com(int n, int k) const noexcept {
		if (n < k || n < 0 || k < 0) return 0;
		return fact_[n] * finv_[k] * finv_[n-k];
	}
	constexpr T fact(int n) const noexcept {
		if (n < 0) return 0;
		return fact_[n];
	}
	constexpr T inv(int n) const noexcept {
		if (n < 0) return 0;
		return inv_[n];
	}
	constexpr T finv(int n) const noexcept {
		if (n < 0) return 0;
		return finv_[n];
	}
};
 
const int MOD = 1000000007;
// const int MOD = 
using mint = Fp<MOD>;
BiCoef<mint> bc;
// bc.init(500050);

int dp[52][1ll<<18];

signed main(){
	int N;
	in(N);
	auto a = mv(N),b = a;
	in(a,b);
	REP(i,52)REP(j,1ll<<N)dp[i][j] = INF;
	dp[0][0] = 0;
	REP(i,1ll<<N){
		int Unused = 0;
		int count = __builtin_popcount(i);
		REP(j,N){
			if(i & (1ll << j)){continue;}
			int cost;
			if(count % 2 == j % 2)cost = a[j];
			else cost = b[j];
			int move = Unused;
			REP(k,51){
				if(dp[k][i] == INF)continue;
				if(cost < k)continue;
				CHMIN(dp[cost][i^(1ll<<j)],dp[k][i]+move);
			}
			Unused++;
		}
	}
	int ans = INF;
	REP(k,51){
		if(dp[k][(1ll << N) - 1] == INF)continue;
		CHMIN(ans,dp[k][(1ll << N) - 1]);
	}
	if(ans == INF)out(-1);
	else out(ans);
}

Measured memory_bytes: 106752