Sorting Pairs Write a program which print coordinates (xi,yi) of given n points on the plane by the following criteria.

 first by x-coordinate in case of a tie, by y-coordinate

The input is given in the following format. 

n

x0 y0 

x1 y1

 : 

xn−1 yn−1

 In the first line, the number of points n is given. In the following n lines, coordinates of each point are given.

5
4 7
5 5
2 3
6 8
2 1

2 1
2 3
4 7
5 5
6 8

1≤n≤100,000

 −1,000,000,000≤xi,yi≤1,000,000,000