Score : $300$ points

问题描述

如果有满足以下条件的不小于 $0$ 的整数，请输出其中最小的一个；否则，输出 -1。

• 此整数以十进制表示时恰好有 $N$ 位数字。（我们假设 $0$ 是一个 $1$ 位整数。对于其他整数，不允许前导零。）
• 从左数第 $s_i$ 位的数字为 $c_i$。$\left(i = 1, 2, \cdots, M\right)$

以上为通义千问 qwen-max 翻译，仅供参考。

Problem Statement

If there is an integer not less than $0$ satisfying the following conditions, print the smallest such integer; otherwise, print -1.

• The integer has exactly $N$ digits in base ten. (We assume $0$ to be a $1$-digit integer. For other integers, leading zeros are not allowed.)
• The $s_i$-th digit from the left is $c_i$. $\left(i = 1, 2, \cdots, M\right)$

Constraints

• All values in input are integers.
• $1 \leq N \leq 3$
• $0 \leq M \leq 5$
• $1 \leq s_i \leq N$
• $0 \leq c_i \leq 9$

Input

Input is given from Standard Input in the following format:

$N$ $M$

$s_1$ $c_1$

$\vdots$

$s_M$ $c_M$

Output

Print the answer.

Sample Input 1

3 3
1 7
3 2
1 7

Sample Output 1

702

$702$ satisfies the conditions - its $1$-st and $3$-rd digits are 7 and 2, respectively - while no non-negative integer less than $702$ satisfies them.

Sample Input 2

3 2
2 1
2 3

Sample Output 2

-1

Sample Input 3

3 1
1 0

Sample Output 3

-1

update @ 2024/3/10 17:14:21