#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 100'000 + 10;
int n, q, maxW;
vector<pair<int, int>> ad[N];
struct Edge {
int u, v, w;
friend istream& operator >> (istream& is, auto& rhs) {
return is >> rhs.u >> rhs.v >> rhs.w;
}
} edge[N];
int sz[N], par[N];
void dfs1(int u, int p = -1) {
for (const auto& [v, w] : ad[u]) {
if (v == p) continue;
par[v] = u;
dfs1(v, u);
sz[u] += sz[v] + 1;
}
}
int head[N], st[N], ed[N], rvs[N], it;
void hld(int u, int p = -1) {
if (!head[u]) head[u] = u;
st[u] = ++it; rvs[it] = u;
sort(ad[u].begin(), ad[u].end(), [&](const auto& a, const auto& b) {
return sz[a.first] > sz[b.first];
});
bool heavy = false;
for (const auto& [v, w] : ad[u]) {
if (v == p) continue;
if (!heavy) head[v] = head[u], hld(v, u);
else hld(v, u);
heavy = true;
}
ed[u] = it;
}
struct IT {
int f[N << 2], lazy[N << 2];
void push(int s) {
f[s << 1] += lazy[s]; f[s << 1 | 1] += lazy[s];
lazy[s << 1] += lazy[s]; lazy[s << 1 | 1] += lazy[s];
lazy[s] = 0;
}
void update(int s, int l, int r, int u, int v, int x) {
if (v < l || u > r) return;
if (u <= l && r <= v) {
f[s] += x;
lazy[s] += x;
return;
}
push(s);
int mid = l + r >> 1;
update(s << 1, l, mid, u, v, x); update(s << 1 | 1, mid + 1, r, u, v, x);
f[s] = max(f[s << 1], f[s << 1 | 1]);
}
void assign(int s, int l, int r, int i, int x) {
if (i < l || i > r) return;
if (l == r) {
f[s] = x;
lazy[s] = 0;
return;
}
push(s);
int mid = l + r >> 1;
assign(s << 1, l, mid, i, x); assign(s << 1 | 1, mid + 1, r, i, x);
f[s] = max(f[s << 1], f[s << 1 | 1]);
}
int query(int s, int l, int r, int u, int v) {
if (v < l || u > r) return -20'000'000'000'000'000;
if (u <= l && r <= v) return f[s];
push(s);
int mid = l + r >> 1;
return max(query(s << 1, l, mid, u, v), query(s << 1 | 1, mid + 1, r, u, v));
}
int lower_bound(int s, int l, int r, int x) {
if (l == r) return l;
push(s);
int mid = l + r >> 1;
if (f[s << 1] >= x) return lower_bound(s << 1, l, mid, x);
return lower_bound(s << 1 | 1, mid + 1, r, x);
}
} D, T;
void dfs2(int u, int p = -1) {
for (const auto& [v, w] : ad[u]) {
if (v == p) continue;
D.update(1, 1, n, st[v], ed[v], w);
dfs2(v, u);
}
T.update(1, 1, n, st[u], st[u], -2 * D.query(1, 1, n, st[u], st[u]));
int heavy = (ad[u].size() - (u != 1) <= 1 ? 0 : ad[u][u != 1].first);
if (!heavy) return;
T.update(1, 1, n, st[u], st[u], D.query(1, 1, n, ed[heavy] + 1, ed[u]));
}
void update(int i, int nW) {
auto [u, v, w] = edge[i];
edge[i].w = nW;
if (st[u] > st[v] ) swap(u, v);
D.update(1, 1, n, st[v], ed[v], nW - w);
T.update(1, 1, n, st[v], ed[v], w - nW);
while (u) {
T.assign(1, 1, n, st[u], 0);
T.update(1, 1, n, st[u], st[u], -2 * D.query(1, 1, n, st[u], st[u]));
int heavy = (ad[u].size() - (u != 1) <= 1 ? 0 : ad[u][u != 1].first);
if (heavy)
T.update(1, 1, n, st[u], st[u], D.query(1, 1, n, ed[heavy] + 1, ed[u]));
if (u == 1) break;
u = par[head[u]];
}
}
int get() {
int d = D.f[1],
u = rvs[D.lower_bound(1, 1, n, d)],
ret = 0;
while (u) {
int minus = 2 * D.query(1, 1, n, st[par[head[u]]], st[par[head[u]]]);
ret = max(ret, T.query(1, 1, n, st[head[u]], st[u] - 1));
ret = max(ret, D.query(1, 1, n, st[par[head[u]]], st[head[u]] - 1) - minus);
ret = max(ret, D.query(1, 1, n, ed[head[u]] + 1, ed[par[head[u]]]) - minus);
if (u == 1) break;
u = par[head[u]];
}
return ret + d;
}
int32_t main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n >> q >> maxW;
for (int i = 0; i < n - 1; ++i) {
cin >> edge[i];
const auto& [u, v, w] = edge[i];
ad[u].push_back({v, w});
ad[v].push_back({u, w});
}
dfs1(par[1] = 1); hld(1);
dfs2(1);
int siesta = 0;
while (q--) {
int i, nW; cin >> i >> nW;
i = (i + siesta) % (n - 1);
nW = (nW + siesta) % maxW;
update(i, nW);
cout << (siesta = get()) << "\n";
}
}
