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 n, m;
int chk[100001];
struct edg {
    int idx, dst;
};
vector<edg> gph[100001];
int dst[100001];

void go(int now, int cnt) {
    dst[now] = cnt;
    chk[now] = 1;
    for (edg nxt : gph[now]) {
        if (!chk[nxt.idx]) {
            go(nxt.idx, cnt+nxt.dst);
        }
        else {
            if (dst[nxt.idx] != cnt+nxt.dst) {
                puts("No");
                exit(0);
            }
        }
    }
}

int main() {
    scanf("%d %d", &n, &m);
    while (m--) {
        int u, v, w;
        scanf("%d %d %d", &u, &v, &w);
        gph[u].push_back({ v,w });
        gph[v].push_back({ u,-w });
    }

    for (int i = 1; i <= n; i++) {
        if (!chk[i]) {
            go(i, 0);
        }
    }

    puts("Yes");

    return 0;
}