URI Online Judge | 2589
# The Biggest Prime Gap

**Timelimit: 1**

By Ricardo Martins, IFSULDEMINAS Brazil

Prime gap refers to the difference between consecutive prime numbers. For example, the distance between prime 7 and 11 is 4, just as the distance between prime 23 and 29 is 6. The challenge is, given a number, considering all previous and the number itself, what is the largest distance between Consecutive prime numbers?

Write a program that, given a number, computes the biggest prime gap.

There will be several test cases. Each test case will have an integer **N** (2 ≤ **N** ≤ 10^{9}). The entry ends with end of file.

For each test case, print the largest distance between consecutive cousins, from 1 to **N**.

Input Sample | Output Sample |

10 |
2 |