Codeforces Testing Round 3


A. Average Numbers
time limit per test: 1 second
memory limit per test: 256 megabytes
input: standard input
output: standard output

Examples
Input
5
1 2 3 4 5
Output
1
3 
Input
4
50 50 50 50
Output
4
1 2 3 4 
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B. Pairs of Numbers
time limit per test: 1 second
memory limit per test: 256 megabytes
input: standard input
output: standard output

Examples
Input
5
Output
3
Input
1
Output
0
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C. Swaps
time limit per test: 2 seconds
memory limit per test: 256 megabytes
input: standard input
output: standard output

Examples
Input
4 8
2 2 2 2
Output
Yes
4
4 3
4 2
1 3
1 2
Input
6 12
1 1 2 2 3 3
Output
Yes
6
6 5
6 4
6 3
5 4
5 3
2 1
Input
5 5
0 0 0 0 5
Output
No
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