/**
 * Matt Kretchmar
 * February 20, 2006
 * Period.java
 * This program searches a sequence of numbers looking for the largest
 * possible period of repeated numbers.
 */

import java.util.Scanner;

class Period
{
    public static void main ( String [] args )
    {
        Scanner keyboard = new Scanner(System.in);
        
        // Read how many numbers in array
        int n = keyboard.nextInt();
        
        // Read in n numbers to store in our array
        int data[] = new int[n];
        for ( int i = 0; i < n; i++ )
        {
            data[i] = keyboard.nextInt();
        }
        
        // We look for possibly periods starting with the smallest possible period length.
        // For each period length, compare numbers that are "period" spaces apart in the 
        // sequence.  If we find any that aren't matches, then this sequence is not periodic
        // with lenght=period.  If all such pairs match, then we have found period, quit and report.
        boolean foundPeriod = false;
        int period = 0;        // potential periods

        while ( !foundPeriod && period < n-1 )
        {
            // Test next period length
            period++;
            
            // Assume this sequence is periodic with length=period
            foundPeriod = true;
            int j = 0;
            // scan through the sequence comparing each pair of numbers that are
            // period spaces apart.
            while ( j+period < n && foundPeriod )
            {
                if ( data[j] != data[j+period] )
                    // if we find a pair that don't match, then no longer possible match
                    foundPeriod = false;
                j++;
            }
        }
                    
        if ( foundPeriod )
            System.out.println("The sequence is periodic with period " + period + ".");
        else
            System.out.println("The sequence is not periodic.");
        
    }
}