Fashion in Berland

1000ms

262144K

Description:

According to rules of the Berland fashion, a jacket should be fastened by all the buttons except only one, but not necessarily it should be the last one. Also if the jacket has only one button, it should be fastened, so the jacket will not swinging open.

You are given a jacket with n buttons. Determine if it is fastened in a right way.

Input:

The first line contains integer n (1 ≤ n ≤ 1000) — the number of buttons on the jacket.

The second line contains n integers a_i (0 ≤ a_i ≤ 1). The number a_i = 0 if the i-th button is not fastened. Otherwise a_i = 1.

Output:

In the only line print the word "YES" if the jacket is fastened in a right way. Otherwise print the word "NO".

Sample Input:

3
1 0 1

Sample Output:

YES

Sample Input:

3
1 0 0

Sample Output:

NO

Informação

Provedor Codeforces

Código CF691A