Problem: There are N people standing on the x-axis. Let the coordinate of Person i be x_i. For every i, x_i is an integer between 0 and 10^9 (inclusive). It is possible that more than one person is standing at the same coordinate.

You will given M pieces of information regarding the positions of these people. The i-th piece of information has the form (L_i, R_i, D_i). This means that Person R_i is to the right of Person L_i by D_i units of distance, that is, x_{R_i} - x_{L_i} = D_i holds.

It turns out that some of these M pieces of information may be incorrect. Determine if there exists a set of values (x_1, x_2, ..., x_N) that is consistent with the given pieces of information.

Constraints

* 1 \leq N \leq 100 000
* 0 \leq M \leq 200 000
* 1 \leq L_i, R_i \leq N (1 \leq i \leq M)
* 0 \leq D_i \leq 10 000 (1 \leq i \leq M)
* L_i \neq R_i (1 \leq i \leq M)
* If i \neq j, then (L_i, R_i) \neq (L_j, R_j) and (L_i, R_i) \neq (R_j, L_j).
* D_i are integers.

Input

Input is given from Standard Input in the following format:


N M
L_1 R_1 D_1
L_2 R_2 D_2
:
L_M R_M D_M


Output

If there exists a set of values (x_1, x_2, ..., x_N) that is consistent with all given pieces of information, print `Yes`; if it does not exist, print `No`.

Examples

Input

3 3
1 2 1
2 3 1
1 3 2


Output

Yes


Input

3 3
1 2 1
2 3 1
1 3 5


Output

No


Input

4 3
2 1 1
2 3 5
3 4 2


Output

Yes


Input

10 3
8 7 100
7 9 100
9 8 100


Output

No


Input

100 0


Output

Yes

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;
const int maxn=1e5+5;
int type[maxn],dis[maxn];
int find(int a)
{
	if(type[a]==a) return a;
	else 
	{
		int pre=type[a];
		type[a]=find(type[a]);
		dis[a]+=dis[pre];
		return type[a];
	}
}
void fl()
{
    freopen(".in","r",stdin);
    freopen(".out","w",stdout);
}
int main()
{
//	  fl();
	ios::sync_with_stdio(0);
	cin.tie(0); cout.tie(0);
	int n,m;
	cin>>n>>m;
	for(int i=1;i<=n;i++)
		type[i]=i;
	bool check=true;
	for(int i=1;i<=m;i++)
	{
		int l,r,d;
		cin>>l>>r>>d;
		if(!check) continue;
		int l_=find(l),r_=find(r);
		if(l_==r_)
		{
			if(dis[r]-dis[l]!=d) check=false;
		}
		else 
		{
			type[r_]=l_;
			dis[r_]=dis[l]+d-dis[r];
		}
	}
	if(check) puts("Yes");
	else puts("No");
	return 0;
}