#include<iostream>
using namespace std;
void swap(int &a, int &b)
{
	int temp = a;
	a = b;
	b = temp;
}
void BucketSort(int a[], int n)
{
	for (int i = 0; i < n;i++)
	{
		while (a[i] != i + 1)
		{
			if (a[i]<=0 || a[i]>n || a[i] == a[a[i] - 1])
				break;
			swap(a[i], a[a[i] - 1]);
		}
	}
}
int FirstMissingPositive(int a[], int n)
{
	BucketSort(a, n);
	for (int i = 0; i < n; i++)
		if (a[i] != i + 1)
			return i + 1;
	return n + 1;
}
int main()
{
	const int n = 6;
	int a[n] = { 2, 0, 6, 3, 4, 1 };
	BucketSort(a, n);
	
	int first = FirstMissingPositive(a, n);
	cout << first << endl;
}