#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
int n, q;
vector <pair <int, long long>> g[N];
int a[N], in[N], out[N], ti, euler[N * 3];
long long d[N];
void dfs(int u, int p) {
in[u] = ++ti;
euler[ti] = u;
for (auto [v, w]: g[u]) {
if (v == p) continue;
d[v] = d[u] + w;
dfs(v, u);
euler[++ti] = u;
}
out[u] = ti;
}
struct node {
long long mx, mn;
long long uw, wv;
long long uwv;
long long lazy;
node operator + (const node& other) const {
node ret;
ret.mn = min(mn, other.mn);
ret.mx = max(mx, other.mx);
ret.uw = max({uw, other.uw, mx - 2 * other.mn});
ret.wv = max({wv, other.wv, other.mx - 2 * mn});
ret.uwv = max({uwv, other.uwv, uw + other.mx, other.wv + mx});
ret.lazy = 0;
return ret;
}
} st[N * 12];
void push(int id, long long delta) {
st[id].mx += delta;
st[id].mn += delta;
st[id].uw -= delta;
st[id].wv -= delta;
st[id].lazy += delta;
}
void build(int id, int L, int R) {
if (L == R) {
st[id].mx = st[id].mn = d[euler[L]];
st[id].uw = st[id].wv = - d[euler[L]];
st[id].uwv = st[id].lazy = 0;
return;
}
int mid = L + R >> 1;
build(id * 2, L, mid);
build(id * 2 + 1, mid + 1, R);
st[id] = st[id * 2] + st[id * 2 + 1];
}
void add(int id, int L, int R, int u, int v, long long delta) {
if (u > R || L > v) return;
if (u <= L && R <= v) {
push(id, delta);
return;
}
if (st[id].lazy) {
push(id * 2, st[id].lazy);
push(id * 2 + 1, st[id].lazy);
st[id].lazy = 0;
}
int mid = L + R >> 1;
add(id * 2, L, mid, u, v, delta);
add(id * 2 + 1, mid + 1, R, u, v, delta);
st[id] = st[id * 2] + st[id * 2 + 1];
}
long long lambda, last;
int main() {
ios :: sync_with_stdio(0); cin.tie(0);
cin >> n >> q >> lambda;
vector <tuple <int, int, long long>> edges;
for (int i = 1; i < n; ++i) {
int u, v;
long long w;
cin >> u >> v >> w;
g[u].push_back({v, w});
g[v].push_back({u, w});
edges.push_back({u, v, w});
}
dfs(1, 0);
build(1, 1, ti);
while (q--) {
int i;
long long w;
cin >> i >> w;
i = (last + i) % (n - 1);
w = (last + w) % lambda;
auto &[u, v, _w] = edges[i];
if (in[u] > in[v]) swap(u, v);
add(1, 1, ti, in[v], out[v], w - _w);
_w = w;
last = st[1].uwv;
cout << last << '\n';
}
}
