SDE Path

Jump Game II

Medium

Jump Game II

Given an array where each element represents the max jump length, find the minimum number of jumps to reach the end.

Input format

The first line contains N. The second line contains N integers (a[i] ≥ 1, reachable guaranteed).

Output format

Print the minimum number of jumps needed to reach the last index.

Constraints

  • Values fit in a 64-bit signed integer
  • Trailing whitespace and a trailing newline are ignored by the judge

Read from stdin, write to stdout. Sample cases below show the exact format.

Sample cases

Example 1
Input
5
2 3 1 1 4
Expected output
2
Example 2
Input
5
2 3 1 1 2
Expected output
2