/// @author Camillus
#include "bits/stdc++.h"
using ll = long long;
using namespace std;
mt19937 rnd(228);
vector<pair<int, int>> g[100500];
int from[100500];
int to[100500];
ll w[100500];
int sz[100500];
bool mark[100500];
void dfs_sz(int u, int p = -1) {
sz[u] = 1;
for (auto [v, i] : g[u]) {
if (v != p && !mark[v]) {
dfs_sz(v, u);
sz[u] += sz[v];
}
}
}
namespace detail {
int component_size;
int level;
int centoid;
};
int get_centroid(int u, int p = -1) {
for (auto [v, i] : g[u]) {
if (v != p && !mark[v] && sz[v] * 2 > detail::component_size) {
return get_centroid(v, u);
}
}
return u;
}
int vertex_centroid[20][100500];
int tin[20][100500];
int tout[20][100500];
int timer[20];
namespace st {
static constexpr int size = 1 << 17;
struct node {
ll max = 0;
ll add = 0;
} tree[20][size * 2 - 1];
} // namespace st
struct segment_tree {
static constexpr int size = st::size;
st::node *tree;
segment_tree(int level) {
tree = st::tree[level];
}
inline void apply(int x, ll v) const {
tree[x].max += v;
tree[x].add += v;
}
inline void push(int x) const {
if (tree[x].add) {
apply(x * 2 + 1, tree[x].add);
apply(x * 2 + 2, tree[x].add);
tree[x].add = 0;
}
}
inline void pull(int x) const {
tree[x].max = max(tree[x * 2 + 1].max, tree[x * 2 + 2].max);
}
inline void set(int i, ll v) const {
int x = size + i - 1;
tree[x].max = v;
while (x) {
x = (x - 1) / 2;
pull(x);
}
}
void add(int l, int r, ll v, int x = 0, int lx = 0, int rx = size) const {
if (l >= rx || lx >= r) {
return;
}
if (l <= lx && rx <= r) {
apply(x, v);
return;
}
push(x);
add(l, r, v, x * 2 + 1, lx, (lx + rx) / 2);
add(l, r, v, x * 2 + 2, (lx + rx) / 2, rx);
pull(x);
}
ll get(int l, int r, int x = 0, int lx = 0, int rx = size) const {
if (l <= lx && rx <= r) {
return tree[x].max;
}
if (l >= rx || lx >= r) {
return 0;
}
push(x);
return max(
get(l, r, x * 2 + 1, lx, (lx + rx) / 2),
get(l, r, x * 2 + 2, (lx + rx) / 2, rx)
);
}
};
namespace st2 {
static constexpr int size = 1 << 17;
ll tree[size * 2 - 1];
void set(int i, ll v) {
int x = size + i - 1;
tree[x] = v;
while (x) {
x = (x - 1) / 2;
tree[x] = max(tree[x * 2 + 1], tree[x * 2 + 2]);
}
}
ll get() {
return tree[0];
}
};
vector<int> centoid_children[100500];
vector<ll> C1[100500];
multiset<ll, greater<ll>> C2[100500];
ll get_centroid_diameter(int u) {
if (C2[u].empty()) {
return 0;
} else if (C2[u].size() == 1) {
return C1[u].back();
} else {
return *C2[u].begin() + *next(C2[u].begin());
}
}
void update_cetroid_diameter(int u) {
st2::set(u, get_centroid_diameter(u));
}
void dfs_centroid(int u, int p = -1, ll d = 0) {
vertex_centroid[detail::level][u] = detail::centoid;
bool is_leaf = true;
for (auto [v, i] : g[u]) {
if (v != p && !mark[v]) {
dfs_centroid(v, u, d + w[i]);
if (is_leaf) {
tin[detail::level][u] = tin[detail::level][v];
}
tout[detail::level][u] = tout[detail::level][v];
is_leaf = false;
}
}
if (is_leaf) {
tin[detail::level][u] = timer[detail::level]++;
tout[detail::level][u] = timer[detail::level];
segment_tree(detail::level).set(tin[detail::level][u], d);
}
}
void dfs_main(int u, int l = 0) {
detail::level = l;
dfs_sz(u);
detail::component_size = sz[u];
u = get_centroid(u);
detail::centoid = u;
mark[u] = true;
dfs_centroid(u);
segment_tree ST(l);
for (auto [v, i] : g[u]) {
if (!mark[v]) {
C1[u].push_back(ST.get(tin[l][v], tout[l][v]));
C2[u].insert(C1[u].back());
centoid_children[u].push_back(v);
dfs_main(v, l + 1);
}
}
update_cetroid_diameter(u);
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, q;
cin >> n >> q;
ll W;
cin >> W;
for (int i = 0; i < n - 1; i++) {
int u, v;
cin >> u >> v >> w[i];
from[i] = u;
to[i] = v;
g[u].emplace_back(v, i);
g[v].emplace_back(u, i);
}
dfs_main(1);
ll last = 0;
while (q--) {
ll d, e;
cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % W;
int u = from[d];
int v = to[d];
ll change = e - w[d];
w[d] = e;
for (int l = 0; l < 20; l++) {
if (!vertex_centroid[l][u] || vertex_centroid[l][u] != vertex_centroid[l][v]) {
break;
}
int c = vertex_centroid[l][u];
int L = max(tin[l][u], tin[l][v]);
int R = min(tout[l][u], tout[l][v]);
segment_tree ST(l);
ST.add(L, R, change);
auto it = upper_bound(centoid_children[c].begin(), centoid_children[c].end(), L, [&l](int L, int u) -> bool {
return L < tin[l][u];
});
it = prev(it);
int i = it - centoid_children[c].begin();
int U = centoid_children[c][i];
C2[c].erase(C2[c].find(C1[c][i]));
C1[c][i] = ST.get(tin[l][U], tout[l][U]);
C2[c].insert(C1[c][i]);
update_cetroid_diameter(c);
}
last = st2::get();
cout << last << '\n';
}
return 0;
}
