Stack
时间限制：C/C++/Rust/Pascal 1秒，其他语言2秒
空间限制：C/C++/Rust/Pascal 256 M，其他语言512 M
Special Judge, 64bit IO Format: %lld

题目描述

ZYT had a magic permutation , and he constructed a sequence by the following pseudo code: 
Stk is an empty stack
for i = 1 to n :
    while ( Stk is not empty ) and ( Stk's top > a[i] ) : 
        pop Stk
    push a[i]
    b[i]=Stk's size
But he somehow forgot the permutation , and only got some  elements of b_i.

Construct a permutation  satisfying these b_i , or determine no such permutation exists.

Here a permutation refers to a sequence that contains all integers from  to  exactly once.

输入描述:

The first line contains two integers , — the length of the permutation, the number of  left b_i.

Then  lines each contains two integer p_i,x_i, denoting that .

输出描述:

Output one line with n integers  — a possible permutation.

If no such permutation exists, output one integer -1.
示例1

输入

复制 
5 2
2 2
5 4

输出

复制 
1 2 5 3 4
示例2

输入

复制 
10 1
1 10

输出

复制 
-1

备注:

It's guaranteed that , and .