public static void Solve()
{
var n = I;
var m = I;
var l = new int[m];
var r = new int[m];
var d = new long[m];
var gr = new AdjacencyList <long>(n);
Repeat(m, i =>
{
l[i] = I - 1;
r[i] = I - 1;
d[i] = L;
gr.Add(l[i], r[i], d[i]);
gr.Add(r[i], l[i], -d[i]);
});
var x = new long[n];
foreach (var edge in gr.DepthFirstSearch())
{
x[edge.Target] = x[edge.Source] + edge.Cost;
}
Repeat(m, j => { if (x[r[j]] - x[l[j]] != d[j])
{
Answer(No);
}
});
Answer(Yes);
}