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**Task** | Statistics

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

You want to travel from Syrjälä to Lehmälä by plane using a minimum-price route. Which cities will you certainly visit?

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

After this, there are $m$ lines that describe 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.

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.

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

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

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

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

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