In africa jungle , there were zebra's who liked to spit.
There owner watched them for whole day and noted in his sheet where each zebra spitted.
Now he's in a confusion and wants to know if in the jungle there are two zebra's which spitted at each other.
Help him solve this task.
If the zebra is present in position a spits b metres right , he can hit only zebra in position a+b , if such a zebra exists.

-----Input:-----
- The first line contains integer t(1<=t<100)- amount of zebras in jungle.
- Each of following t lines contains two integers a(i) and b(i)(-10^4<=x(i)<=10^4,1<|d(i)|<=2.10^4) - records in owner sheet.
- a(i) is the position of i-th zebra and b(i) is distance at which the i-th camel spitted.
Positive values of d(i) correspond to spits right, negative values correspond to spit left.No two zebras may stand in the same position.

-----Output:-----
If there are two zebras , which spitted at each other , output YES, otherwise , output NO.

-----Sample Input:-----
2
0 1
1 -1

-----Sample Output:-----
YES

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