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;
int f[100010],d[100010];
int findd(int x)
{
    if(f[x]==x) return x;
    int a=f[x];
    int b=findd(f[x]);
    d[x]+=d[a];
    f[x]=b;
    return b;
}
bool unit(int x,int y,int c)
{
    int fx=findd(x);
    int fy=findd(y);
    if(fx==fy)
    {
        if(d[y]-d[x]==c) return 1;
        else return 0;
    }
    f[fy]=fx;
    d[fy]=d[x]+c-d[y];
    return 1;
}
int main()
{
    int n,m;
    while(~scanf("%d%d",&n,&m))
    {
        int flag=0;
        int l,r,d;
        for(int i=1;i<=n;i++)f[i]=i;
        for(int i=0;i<m;i++)
        {
            scanf("%d%d%d",&l,&r,&d);
            if(!unit(l,r,d))
            {
                flag=1;
            }
        }
        if(flag) cout<<"No"<<endl;
        else cout<<"Yes"<<endl;
    }
}