Arithmetic Progression Subsequences (2)

Write a program that reads an integer n > 1 followed by a sequence of
integers, and finds out whether the sequence contains a consecutive
subsequence of length n that forms an arithmetic progression.

A consecutive subsequence of integers forms an arithmetic progression if
the difference between two consecutive numbers equals a fixed integer
value r. For instance, 4567 is an arithmetic progression with r = 1, and
2233445566 is an arithmetic progression with r = 11.

If the input sequence contains such a progression, the program must
report the start number and the value r. Otherwise, the program must
indicate "No arithmetic progression of length n found".

Input

The input is an integer n > 1, followed by a sequence of integers
containing at least 2 elements.

Output

If a progression subsequence of length n exists, the output is the first
element of the subsequence and the value of r. Otherwise, the output is
"No arithmetic progression of length n found".

Problem information

Author: ProAl

Generation: 2026-01-25T16:57:37.367Z

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