PermutarePow_50p

#include <bits/stdc++.h>
#define N 1000005
using namespace std;
ifstream fin("permutarepow.in");
ofstream fout("permutarepow.out");
int n,permutation[N];
unsigned long long int maxlen=1;
typedef void(*cyclefn)(const int *,unsigned long long int);

unsigned long long int gcd(unsigned long long int a,unsigned long long int b)
{
    if(b==0)
        return a;
    return gcd(b,a%b);
}

void permutation_cycles_recursive(const int *permutation,int *visited,int start,int current,int *path,int length,cyclefn fun)
{
    visited[current]=1;
    path[length]=current;
    if(start==current&&length>0)
        fun(path,length);
    else
        permutation_cycles_recursive(permutation,visited,start,permutation[current],path,length+1,fun);
}

void permutation_cycles(const int *permutation,int n,cyclefn fun)
{
    int *visited=new int[n];
    int *path=new int[n];
    if(!(visited&&path))
    {
        free(visited);
        free(path);
        return;
    }
    for(int i=0;i<n;++i)
        if(!visited[i])
            permutation_cycles_recursive(permutation,visited,i,i,path,0,fun);
    free(visited);
    free(path);
}

void print(const int *cycle,unsigned long long int length)
{
    if(length>1)
        maxlen=1ULL*maxlen*length /gcd(maxlen,length);
}

int main()
{
    fin>>n;
    for(int i=1;i<=n;++i)
        fin>>permutation[i];
    ++n;
    permutation_cycles(permutation,n,print);
    fout<<maxlen;
    return 0;
}