/*
Dynamic Diameter
https://oj.uz/problem/view/CEOI19_diameter
*/
#include <bits/stdc++.h>
using namespace std;
const int N = 1e5, N_ = N * 2 - 1;
struct dat {
long long a, b, ab, bc, abc;
void lazy(long long x) {
a += x;
b -= 2 * x;
ab -= x;
bc -= x;
}
dat operator+(const dat& o) const {
return {
max(a, o.a),
max(b, o.b),
max(a + o.b, max(ab, o.ab)),
max(b + o.a, max(bc, o.bc)),
max(max(a + o.bc, ab + o.a), max(abc, o.abc))
};
}
} t[N_ * 4];
long long lz[N_ * 4];
vector<pair<int, long long>> g[N];
int d[N], in[N], out[N], tt;
void dfs(int p, int i) {
in[i] = tt++;
for (auto [j, c] : g[i])
if (p != j)
d[j] = d[i] + 1, dfs(i, j), tt++;
out[i] = tt - 1;
}
void put(int k, long long x) {
t[k].lazy(x);
lz[k] += x;
}
void push(int k) {
if (lz[k] != 0)
put(k << 1 | 0, lz[k]), put(k << 1 | 1, lz[k]), lz[k] = 0;
}
void update(int k, int l, int r, int ql, int qr, long long x) {
if (ql > r || qr < l)
return;
else if (ql <= l && qr >= r)
put(k, x);
else {
int m = (l + r) / 2;
push(k);
update(k << 1 | 0, l, m, ql, qr, x), update(k << 1 | 1, m + 1, r, ql, qr, x);
t[k] = t[k << 1 | 0] + t[k << 1 | 1];
}
}
int main() {
ios::sync_with_stdio(0), cin.tie(0);
int n, q;
long long A;
cin >> n >> q >> A;
static tuple<int, int, long long> e[N - 1];
for (int h = 0; h < n - 1; h++) {
int i, j;
long long c;
cin >> i >> j >> c, i--, j--;
g[i].push_back({j, c}), g[j].push_back({i, c});
e[h] = {i, j, c};
}
tt = 0;
dfs(-1, 0);
assert(tt <= N_);
for (int h = 0; h < n - 1; h++) {
auto &[i, j, c] = e[h];
if (d[i] < d[j])
swap(i, j);
update(1, 0, tt - 1, in[i], out[i], c);
}
long long last = 0;
while (q--) {
int h;
long long c;
cin >> h >> c, h = (h + last) % (n - 1), c = (c + last) % A;
auto &[i, j, c_] = e[h];
update(1, 0, tt - 1, in[i], out[i], c - c_), c_ = c;
cout << (last = t[1].abc) << '\n';
}
return 0;
}
