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:
import sys
INF=10**9
N,M=map(int,input().split())

graph=[]
for i in range(N+1):
  graph.append([])

for i in range(M):
  L,R,D=map(int,input().split())
  graph[L].append((R,D))
  graph[R].append((L,-D))
#print(graph)

pos_list=[-INF]*(N+1)
for i in range(1,N+1):
  if pos_list[i]!=-INF:
    continue
    
  queue={i}
  pos_list[i]=0
  while(len(queue)>0):
    new_queue=set()
    for q in queue:
      for v,d in graph[q]:
        if pos_list[v]==-INF:
          pos_list[v]=pos_list[q]+d
          new_queue.add(v)
        elif pos_list[v]!=pos_list[q]+d:
          print("No")
          sys.exit(0)
          
    queue=new_queue
          
#print(pos_list[1:])
print("Yes")