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
readline = sys.stdin.readline
class UFP():
    def __init__(self, num):
        self.par = [-1]*num
        self.dist = [0]*num
    def find(self, x):
        if self.par[x] < 0:
            return x
        else:
            res = 0
            xo = x
            while self.par[x] >= 0:
                res += self.dist[x]
                x = self.par[x]
            self.dist[xo] = res
            self.par[xo] = x
            return x
    
    def union(self, x, y, d):
        rx = self.find(x)
        ry = self.find(y)
        if rx != ry:
            if self.par[rx] > self.par[ry]:
                rx, ry = ry, rx
                x, y = y, x
                d = -d
            self.par[rx] += self.par[ry]
            self.par[ry] = rx
            self.dist[ry] = d + self.dist[x] - self.dist[y]
            return True
        else:
            if d + self.dist[x] - self.dist[y]:
                return False
            return True

N, M = map(int, readline().split())
T = UFP(N)
ans = 'No'
for _ in range(M):
    l, r, d = map(int, readline().split())
    l -= 1
    r -= 1
    if not T.union(l, r, d):
        break
else:
    ans = 'Yes'
print(ans)