#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>
#include <cstring>
using namespace std;
typedef long long LL;
typedef complex<double> CMP;

class PerfectPermutation { public:
	int reorder(vector <int> P) 
	{
		vector<bool> used(P.size(), false);

		int num_loop = 0;
		for(int i=0; i<P.size(); ++i)
			if( !used[i] ) {
				++num_loop;

				for(int p=i; !used[p]; p=P[p])
					used[p] = true;
			}
		return num_loop==1 ? 0 : num_loop;
	}
};

// 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(_, PerfectPermutation().reorder(P));}
int main(){

CASE(0)
	int P_[] = {2, 0, 1};
	  vector <int> P(P_, P_+sizeof(P_)/sizeof(*P_)); 
	int _ = 0; 
END
CASE(1)
	int P_[] = {2, 0, 1, 4, 3};
	  vector <int> P(P_, P_+sizeof(P_)/sizeof(*P_)); 
	int _ = 2; 
END
CASE(2)
	int P_[] = {2, 3, 0, 1};
	  vector <int> P(P_, P_+sizeof(P_)/sizeof(*P_)); 
	int _ = 2; 
END
CASE(3)
	int P_[] = {0, 5, 3, 2, 1, 4};
	  vector <int> P(P_, P_+sizeof(P_)/sizeof(*P_)); 
	int _ = 3; 
END
CASE(4)
	int P_[] = {4, 2, 6, 0, 3, 5, 9, 7, 8, 1};
	  vector <int> P(P_, P_+sizeof(P_)/sizeof(*P_)); 
	int _ = 5; 
END

}
// END CUT HERE
