Package for this problem was not updated by the problem writer or Codeforces administration after we’ve upgraded the judging servers. To adjust the time limit constraint, solution execution time will be multiplied by 2. For example, if your solution works for 400 ms on judging servers, then value 800 ms will be displayed and used to determine the verdict.

Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ACM-ICPC mode for virtual contests.
If you've seen these problems, a virtual contest is not for you - solve these problems in the archive.
If you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.
Never use someone else's code, read the tutorials or communicate with other person during a virtual contest.

No tag edit access

A. Heads or Tails

time limit per test

2 secondsmemory limit per test

256 megabytesinput

standard inputoutput

standard outputPetya and Vasya are tossing a coin. Their friend Valera is appointed as a judge. The game is very simple. First Vasya tosses a coin *x* times, then Petya tosses a coin *y* times. If the tossing player gets head, he scores one point. If he gets tail, nobody gets any points. The winner is the player with most points by the end of the game. If boys have the same number of points, the game finishes with a draw.

At some point, Valera lost his count, and so he can not say exactly what the score is at the end of the game. But there are things he remembers for sure. He remembers that the entire game Vasya got heads at least *a* times, and Petya got heads at least *b* times. Moreover, he knows that the winner of the game was Vasya. Valera wants to use this information to know every possible outcome of the game, which do not contradict his memories.

Input

The single line contains four integers *x*, *y*, *a*, *b* (1 ≤ *a* ≤ *x* ≤ 100, 1 ≤ *b* ≤ *y* ≤ 100). The numbers on the line are separated by a space.

Output

In the first line print integer *n* — the number of possible outcomes of the game. Then on *n* lines print the outcomes. On the *i*-th line print a space-separated pair of integers *c*_{i}, *d*_{i} — the number of heads Vasya and Petya got in the *i*-th outcome of the game, correspondingly. Print pairs of integers (*c*_{i}, *d*_{i}) in the strictly increasing order.

Let us remind you that the pair of numbers (*p*_{1}, *q*_{1}) is less than the pair of numbers (*p*_{2}, *q*_{2}), if *p*_{1} < *p*_{2}, or *p*_{1} = *p*_{2} and also *q*_{1} < *q*_{2}.

Examples

Input

3 2 1 1

Output

3

2 1

3 1

3 2

Input

2 4 2 2

Output

0

Codeforces (c) Copyright 2010-2017 Mike Mirzayanov

The only programming contests Web 2.0 platform

Server time: Nov/21/2017 09:19:50 (c2).

Desktop version, switch to mobile version.

User lists

Name |
---|