Author: | G. Grenkin, A. Klenin | Time limit: | 1 sec | |
Input file: | input.txt | Memory limit: | 256 Mb | |
Output file: | output.txt |
Two fathers and two sons walked together... It is well known that this could describe a group of either 3 or 4 people.
Now let's say that A fathers and B sons walked together. Could it be that this group consisted of exactly N different persons?
A person is counted as a father if there is his son among the group. A person is counted as a son if there is his father among the group. Each father can have one or more sons, each son must have exactly one father. Father of a person can not be this person's descendant. Each person must me either a son, a father, or both.
Your program must, given numbers A B N, output corresponding father-son relationship or determine that it does not exist.
Input file contains integers A B N.
Output file must contain a number of father-son relationships M followed by M pairs ai bi where ai is a number of the father, bi is a number of the son (1 ≤ ai, bi ≤ N).
All pairs must be different. If there are several solutions, output any of them. If it is impossible for a group to consist of N persons, output file must contain a single integer 0.
1 ≤ A ≤ B ≤ 100
1 ≤ N ≤ 200
No. | Input file (input.txt ) |
Output file (output.txt ) |
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1 |
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2 |
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3 |
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