81. Given an array print the number of subarrays that can be formed with it. Input Size : N <= 100000

Given an array print the number of subarrays that can be formed with it.
Input Size : N <= 100000
Sample Testcase :
INPUT
5
1 2 3 2 1
OUTPUT
15

n=int(input())
a=list(map(int,input().split()))
b=n*(n+1)//2
print(b)