#include #include #include #include using std::cin; using std::cout; using std::endl; const int N = 2e5 + 5; const int mod = 1e9 + 7; int n, m, a[N], f[N]; int cnt, id[N], rid[N], fa[N], dep[N], siz[N], son[N], top[N]; std::vector> g[N]; struct node { int l, r, v, max, sum; node() = default; node(int _l, int _r) : l(_l), r(_r), v(0), max(0), sum(0) {} } tr[N << 2]; void pushup(int u) { tr[u].max = std::max(tr[u << 1].max, tr[u << 1 | 1].max); tr[u].sum = (tr[u << 1].sum + tr[u << 1 | 1].sum) % mod; } void build(int u, int l, int r) { tr[u] = node(l, r); if (l == r) { tr[u].max = a[rid[l]]; tr[u].sum = static_cast(tr[u].max) * f[rid[l]] % mod; return; } int mid = l + r >> 1; build(u << 1, l, mid); build(u << 1 | 1, mid + 1, r); pushup(u); } void dfs1(int u, int f) { fa[u] = f; dep[u] = dep[f] + 1; siz[u] = 1; for (auto e : g[u]) { int v = e.first, w = e.second; if (v == f) continue; a[v] = w; dfs1(v, u); siz[u] += siz[v]; if (siz[son[u]] < siz[v]) son[u] = v; } ::f[u] = static_cast(siz[u]) * (n - siz[u]) % mod; } void dfs2(int u, int t) { rid[id[u] = ++cnt] = u; top[u] = t; if (!son[u]) return; dfs2(son[u], t); for (auto e : g[u]) { int v = e.first; if (v == fa[u]) continue; if (v == son[u]) continue; dfs2(v, v); } } void modify(int u, int l, int r) { if (tr[u].max <= 1) return; if (tr[u].l == tr[u].r) { tr[u].max = std::sqrt(tr[u].max); tr[u].sum = static_cast(tr[u].max) * f[rid[tr[u].l]] % mod; return; } int mid = tr[u].l + tr[u].r >> 1; if (l <= mid) modify(u << 1, l, r); if (r > mid) modify(u << 1 | 1, l, r); pushup(u); } void modify_path(int u, int v) { while (top[u] != top[v]) { if (dep[top[u]] < dep[top[v]]) std::swap(u, v); modify(1, id[top[u]], id[u]); u = fa[top[u]]; } if (u == v) return; if (dep[u] < dep[v]) std::swap(u, v); modify(1, id[v] + 1, id[u]); } int main() { std::ios::sync_with_stdio(false); cin.tie(nullptr); cin >> n >> m; for (int i = 1, u, v, w; i < n; i++) { cin >> u >> v >> w; g[u].emplace_back(v, w); g[v].emplace_back(u, w); } dfs1(1, 1); dfs2(1, 1); build(1, 1, n); cout << tr[1].sum << endl; while (m--) { int u, v; cin >> u >> v; modify_path(u, v); cout << tr[1].sum << endl; } return 0; }