**Time limit:**1.00 s**Memory limit:**512 MB

**Input**

The first input line contains two integers $n$ and $m$: the number of cities and the number of flights. The cities are numbered $1,2,\ldots,n$. City 1 is Syrjälä, and city $n$ is Lehmälä.

After this, there are $m$ lines describing the flights. Each line has three integers $a$, $b$, and $c$: there is a flight from city $a$ to city $b$ with price $c$. All flights are one-way flights.

You may assume that there is a route from Syrjälä to Lehmälä.

**Output**

First print an integer $k$: the number of cities that are certainly in the route. After this, print the $k$ cities sorted in increasing order.

**Constraints**

- $1 \le n \le 10^5$

- $1 \le m \le 2 \cdot 10^5$

- $1 \le a,b \le n$

- $1 \le c \le 10^9$

**Example**

Input:

`5 6`

1 2 3

1 3 4

2 3 1

2 4 5

3 4 1

4 5 8

Output:

`4`

1 3 4 5