A10295 | Bear and Three Balls

Limak is a little polar bear. He has $n$ balls, the $i$ -th ball has size $t_{i}$ .

Limak wants to give one ball to each of his three friends. Giving gifts isn't easy — there are two rules Limak must obey to make friends happy:

- No two friends can get balls of the same size.
- No two friends can get balls of sizes that differ by more than $2$ .

For example, Limak can choose balls with sizes $4$ , $5$ and $3$ , or balls with sizes $90$ , $91$ and $92$ . But he can't choose balls with sizes $5$ , $5$ and $6$ (two friends would get balls of the same size), and he can't choose balls with sizes $30$ , $31$ and $33$ (because sizes $30$ and $33$ differ by more than $2$ ).

Your task is to check whether Limak can choose three balls that satisfy conditions above.

The first line of the input contains one integer $n$ ( $3<=n<=50$ ) — the number of balls Limak has.

The second line contains $n$ integers $t_{1},t_{2},...,t_{n}$ ( $1<=t_{i}<=1000$ ) where $t_{i}$ denotes the size of the $i$ -th ball.

Print "YES" (without quotes) if Limak can choose three balls of distinct sizes, such that any two of them differ by no more than $2$ . Otherwise, print "NO" (without quotes).