题目描述 Given $N + 1$ integers between $1$ and $n$, find the number that is duplicated. 输入格式 The first line contains an integer $n$ ($1 \leq n \leq 10^5$). The second line contains $N + 1$ integers separated by spaces, each between $1$ and $n$. 输出格式 Output the duplicated number. 输入样例 5 1 2 3 4 2 5 输出样例 2