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 PYTHON3):

Solution:
# -*- coding: utf-8 -*-
from collections import deque
n,m = map(int, input().split())
edge = {}
for _ in range(m):
    l,r,d = map(int,input().split())
    if l not in edge:
        edge[l] = []
    edge[l].append([r,d])
    if r not in edge:
        edge[r] = []
    edge[r].append([l,-1*d])
# print(edge)
x = [None for _ in range(n+1)]

for i in range(1,n+1):
    if x[i] is None:
        x[i] = 0
        q = deque([i])
        while len(q)>0:
            v = q.popleft()
            if v not in edge:
                break
            for u,d in edge[v]:
                # print(v,u,d,x)
                if x[u] is None:
                    x[u] = x[v]+d
                    q.append(u)
                elif x[u]!=x[v]+d:
                    print("No")
                    exit()
        # print(x)

print("Yes")