Problem: Natural numbers are the set of positive integers, which ranges from 1 to infinity excluding fractional part. Natural numbers are whole numbers excluding zero. Zero is the only whole number which is not a natural number. An array is special if all the elements are natural numbers. Find whether the given array is special or not.

Input: The first line of input contains a single integer N denoting the array size.

 The second line of input contains N-space separated integers denoting the array.

Output: Print "Yes" if the array is special else print "No".

Constraints: 1<=N<=100.

0<=Arrays elements<=100.

Sample Input: 4

0 1 2 3

Sample Output: 

No

input()
print('No' if '0' in input().split() else 'Yes')