# include <iostream>
# include <algorithm>

using namespace std;

struct pole
{
	int first;
	int last;
	int index;
};

//int out[10000];
//pole column[10000];

bool fun ( pole p1, pole p2 ) { return ( p1.last < p2.last ); }

int main()
{
	int n,i,index;
	cin >> n;
	int *out = new int[n];
	pole *column = new pole[n];
	bool *empty = new bool[n];
	for ( i=0; i<n; i++)
	{
		cin >> column[i].first;
		cin >> column[i].last;

		out[i] = -1;
		column[i].index = i;
		empty[i] = true;
	}

	sort(&column[0],&column[n],fun);

	index = 0;
	for ( i=0; i<n; i++ )
	{
		while ( column[i].first <= column[i].last )
		{
			if (  empty[column[i].first] )
			{
				out[column[i].index] = column[i].first;
				empty[column[i].first] = false;
				break;
			}
			column[i].first++;
		}
	}
	bool ok = true;
	for (i=0;i<n;i++)
		if ( out[i] == -1 )
		{
			ok = false;
			break;
		}

	if ( ok )
		for (i=0;i<n;i++)
			cout << out[i] << endl;
	else
		cout << "NIE";

	//system("Pause");
	return 0;
}