Given an array of positive numbers, which size is $N$, and a positive number $S$, find the length of the smallest contiguous subarray whose sum is greater than or equal to $S$. Return $0$ if no such subarray exists.

Two lines.
The first line contains two positive numbers, $N$ $(2 \leq N \leq 2*10^5)$ and $S$ $(1 \leq S \leq 10^4)$。.
The second line contains $N$ positive numbers, $a_i$ ($1 \leq a_i \leq 10^6$).

One positive number, the answer.

2

The smallest subarray with a sum great than or equal to $7$ is $[5, 2]$. So the answer is $2$.