Score : $200$ points

问题描述

有 $N$ 个人。第 $i$ 个（$1 \leq i \leq N$）人的姓氏和名字分别为 $S_i$ 和 $T_i$。

判断是否存在一对人具有相同的姓氏和名字。换句话说，判断是否存在一对整数 $(i,j)$ 满足 $1 \leq i < j \leq N$，且 $S_i=S_j$ 以及 $T_i=T_j$。

以上为通义千问 qwen-max 翻译，仅供参考。

Problem Statement

There are $N$ people. The family name and given name of the $i$-th person $(1 \leq i \leq N)$ are $S_i$ and $T_i$, respectively.

Determine whether there is a pair of people with the same family and given names. In other words, determine whether there is a pair of integers $(i,j)$ such that $1 \leq i \lt j \leq N$, $S_i=S_j$, and $T_i=T_j$.

Constraints

• $2 \leq N \leq 1000$
• $N$ is an integer.
• Each of $S_i$ and $T_i$ is a string of length between $1$ and $10$ (inclusive) consisting of English lowercase letters.

Input

Input is given from Standard Input in the following format:

$N$

$S_1$ $T_1$

$S_2$ $T_2$

$\hspace{0.6cm}\vdots$

$S_N$ $T_N$

Output

If there is a pair of people with the same family and given names, print Yes; otherwise, print No.

Sample Input 1

3
tanaka taro
sato hanako
tanaka taro

Sample Output 1

Yes

The first and third persons have the same family and given names.

Sample Input 2

3
saito ichiro
saito jiro
saito saburo

Sample Output 2

No

No two persons have the same family and given names.

Sample Input 3

4
sypdgidop bkseq
bajsqz hh
ozjekw mcybmtt
qfeysvw dbo

Sample Output 3

No

update @ 2024/3/10 09:34:36