E. Flow
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

One of Pang's research interests is the maximum flow problem.

A directed graph $$$G$$$ with $$$n$$$ vertices is universe if the following condition is satisfied:

  • $$$G$$$ is the union of $$$k$$$ vertex-independent simple paths from vertex $$$1$$$ to vertex $$$n$$$ of the same length.
A set of paths is vertex-independent if they do not have any internal vertex in common.

A vertex in a path is called internal if it is not an endpoint of that path.

A path is simple if its vertices are distinct.

Let $$$G$$$ be a universe graph with $$$n$$$ vertices and $$$m$$$ edges. Each edge has a non-negative integral capacity. You are allowed to perform the following operation any (including $$$0$$$) times to make the maximum flow from vertex $$$1$$$ to vertex $$$n$$$ as large as possible:

Let $$$e$$$ be an edge with positive capacity. Reduce the capacity of $$$e$$$ by $$$1$$$ and increase the capacity of another edge by $$$1$$$.

Pang wants to know what is the minimum number of operations to achieve it?

Input

The first line contains two integers $$$n$$$ and $$$m$$$ ($$$2\leq n\leq 100000, 1\leq m \leq 200000$$$).

Each of the next $$$m$$$ lines contains three integers $$$x, y$$$ and $$$z$$$, denoting an edge from $$$x$$$ to $$$y$$$ with capacity $$$z$$$ ($$$1 \leq x, y \leq n$$$, $$$0\le z\le 1000000000$$$).

It's guaranteed that the input is a $$$universe$$$ graph without multiple edges and self-loops.

Output

Output a single integer — the minimum number of operations.

Examples
Input
4 3
1 2 1
2 3 2
3 4 3
Output
1
Input
4 4
1 2 1
1 3 1
2 4 2
3 4 2
Output
1