/**
* author: NimaAryan
* created: 2023-12-09 09:11:54
**/
#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#include "algo/debug.h"
#endif
using i64 = long long;
struct Tag {
i64 add = 0;
void apply(Tag v) {
add += v.add;
}
};
struct Info {
i64 min_dep = 0;
i64 max_dep = 0;
/* max(dep[x] - 2 * dep[y]) */
i64 limp = 0;
i64 rimp = 0;
i64 diam = 0;
void apply(Tag v) {
min_dep += v.add;
max_dep += v.add;
limp -= v.add;
rimp -= v.add;
}
};
Info operator+(Info a, Info b) {
Info res;
res.min_dep = min(a.min_dep, b.min_dep);
res.max_dep = max(a.max_dep, b.max_dep);
res.limp = max({a.limp, b.limp, a.max_dep - 2LL * b.min_dep});
res.rimp = max({a.rimp, b.rimp, b.max_dep - 2LL * a.min_dep});
res.diam = max({a.diam, b.diam, a.max_dep + b.rimp, b.max_dep + a.limp});
return res;
}
class LazySegmentTree {
public:
vector<Info> info;
vector<Tag> tag;
int n;
LazySegmentTree(int n) : n(n) {
info.assign(4 << __lg(n), Info());
tag.assign(4 << __lg(n), Tag());
}
void pull(int p) {
info[p] = info[2 * p] + info[2 * p + 1];
}
void apply(int p, const Tag& v) {
info[p].apply(v);
tag[p].apply(v);
}
void push(int p) {
apply(2 * p, tag[p]);
apply(2 * p + 1, tag[p]);
tag[p] = Tag();
}
void range_apply(int p, int l, int r, int lx, int rx,
const Tag& v) {
if (l >= rx || r <= lx) {
return;
}
if (l >= lx && r <= rx) {
apply(p, v);
return;
}
int m = (l + r) / 2;
push(p);
range_apply(2 * p, l, m, lx, rx, v);
range_apply(2 * p + 1, m, r, lx, rx, v);
pull(p);
}
void range_apply(int lx, int rx, const Tag& v) {
range_apply(1, 0, n, lx, rx, v);
}
};
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, q;
cin >> n >> q;
i64 w;
cin >> w;
vector<vector<pair<int, i64>>> t(n);
vector<i64> c(n - 1);
for (int i = 0; i < n - 1; ++i) {
int a, b;
cin >> a >> b;
--a, --b;
cin >> c[i];
t[a].emplace_back(b, i);
t[b].emplace_back(a, i);
}
LazySegmentTree seg(2 * n - 1);
vector<int> tin(n - 1), tout(n - 1);
int num = 0;
auto dfs = [&](auto self, int x, int p) -> void {
num++;
for (auto [y, i] : t[x]) {
if (i != p) {
tin[i] = num;
self(self, y, i);
tout[i] = num;
seg.range_apply(tin[i], tout[i], Tag{c[i]});
num++;
}
}
};
dfs(dfs, 0, -1);
i64 last = 0;
while (q--) {
int d;
cin >> d;
i64 e;
cin >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
seg.range_apply(tin[d], tout[d], Tag{-c[d]});
c[d] = e;
seg.range_apply(tin[d], tout[d], Tag{+c[d]});
cout << (last = seg.info[1].diam) << "\n";
}
return 0;
}
