#include <vector>
#include <iterator>
#include <climits>
#include <cstdlib>
using namespace std;

/*vector<long> pari;
vector<long> dispari;
vector<long> id_pari;
vector<long> id_dispari;*/

long long paletta_sort(int N, int V[]) {
	int num = 0;
	
	/*if (N%2==0){
		pari.assign(N/2, 0);
		dispari.assign(N/2, 0);
	}
	else{
		pari.assign((N+1)/2, 0);
		dispari.assign((N-1)/2, 0);
	}
	
	id_pari.assign(N, -1);
	id_dispari.assign(N, -1);*/
	
	
	for (int i = 0; i<N; i++){
		if (V[i]%2 != i%2) return -1;
		
		/*if (i%2 == 0){
			pari[i/2] = V[i];
			id_pari[V[i]] = i/2;
		}
		else{
			dispari[(i-1)/2] = V[i];
			id_dispari[V[i]] = (i-1)/2;
		}*/
	}
	
	int k = 0;
	
	while (k<N)
	{
		if (V[k] != k)
		{
			num += abs(V[k] - k);
			long r = V[k];
			
			int* g = &k;
			int* m = &r;
			
			V.erase(g);
			
			V.insert(m, r);
		}
		else{
			k += 1;
		}
	}
	
	
    return num;
}