Description

Given a sequence {$A_1, A_2, ..., A_N$}, modify the minimum number of elements such that the sequence {$A_N$} becomes an arithmetic sequence with a common difference of 1.

Input Format

Line 1: An integer N.
Line 2: N integers $A_1, A_2, ..., A_N$.

Output Format

An integer representing the minimum number of elements to be modified.

3
2 1 4

1

Hint

【Data Range and Constraints】

For 40% of the data, $n <= 1000$;

For 100% of the data, $n <= 10^5$, $1 <= A_i <= 10^6$.

Source

CodesOnline