/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int[] a = new int[n];
		for(int i=0; i<n; i++){
			a[i] = sc.nextInt();
		}
		//solver
		int lo = -1, hi = n;
 
		while(lo + 1<hi){
			int mid = lo + ( hi -lo ) /2;
			if(a[mid]==0){
				lo = mid;
			} else {
				hi = mid;
			}
		}
		int last0 = (lo==-1 || a[lo]!=0) ? -1 : lo;
		int first1 = (hi==n || a[hi]!=1) ? -1 : hi;
		System.out.println(last0 + "----" + first1);
	}
}

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