#include <bits/stdc++.h>
using namespace std;
#define sz(x) ((int)size(x))
#define all(x) begin(x), end(x)
#define trace(x) cout << #x << ": " << (x) << endl;
typedef long long ll;
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
int rand(int l, int r) { return (int) ((ll) rnd() % (r - l + 1)) + l; }
struct segtree {
int sz = 1;
vector<ll> mx, add;
segtree() = default;
segtree(int n) {
sz = 1;
while (sz < n) {
sz <<= 1;
}
mx.assign(sz << 1, 0), add.assign(sz << 1, 0);
}
void init(int n) {
sz = 1;
while (sz < n) {
sz <<= 1;
}
mx.assign(sz << 1, 0), add.assign(sz << 1, 0);
}
void modify(int l, int r, ll val, int x, int lx, int rx) {
if (l >= rx || lx >= r) {
return;
}
if (l <= lx && rx <= r) {
mx[x] += val;
add[x] += val;
return;
}
int m = (lx + rx) >> 1;
modify(l, r, val, x << 1, lx, m), modify(l, r, val, x << 1 | 1, m, rx);
mx[x] = max(mx[x << 1], mx[x << 1 | 1]) + add[x];
}
void modify(int l, int r, ll val) {
modify(l, r, val, 1, 0, sz);
}
ll get(int l, int r, int x, int lx, int rx) {
if (l >= rx || lx >= r) {
return 0;
}
if (l <= lx && rx <= r) {
return mx[x];
}
int m = (lx + rx) >> 1;
return max(get(l, r, x << 1, lx, m), get(l, r, x << 1 | 1, m, rx)) + add[x];
}
ll get(int l, int r) {
return get(l, r, 1, 0, sz);
}
};
const int N = 100000, logn = 18;
int A[N], B[N], Root[logn][N], Parent[logn][N], Child[logn][N], siz[N], lst[N], tin[logn][N], tout[logn][N], PP[logn][N], sz[N], T = 0;
segtree st[logn][N];
multiset<ll, greater<>> mult[logn][N];
ll W[N], diam[logn][N];
bool used[N];
vector<pair<int, int>> g[N];
int centroid(int v, int n, int p) {
for (auto [to, i]: g[v]) {
if (!used[to] && to != p && sz[to] * 2 > n) {
return centroid(to, n, v);
}
}
return v;
}
void calc_sz(int v, int p) {
sz[v] = 1;
for (auto [to, i]: g[v]) {
if (!used[to] && to != p) {
calc_sz(to, v);
sz[v] += sz[to];
}
}
}
void dfs(int v, int p, int id, int root, int pp) {
Root[siz[v]][id] = root;
Parent[siz[v]][id] = p;
Child[siz[v]][id] = v;
PP[siz[v]][id] = pp;
tin[siz[v]][v] = T++;
for (auto [to, j]: g[v]) {
if (!used[to] && to != p) {
dfs(to, v, j, root, pp);
}
}
tout[siz[v]][v] = T;
st[siz[v]][root].modify(tin[siz[v]][v], tout[siz[v]][v], W[id]);
++siz[v];
}
multiset<ll, greater<>> bestDiam;
void solve(int v) {
used[v] = true;
calc_sz(v, -1);
T = 0;
st[siz[v]][v].init(sz[v]);
for (auto [to, i]: g[v]) {
if (!used[to]) {
dfs(to, v, i, v, to);
mult[siz[v]][v].insert(st[siz[v]][v].get(tin[siz[v]][to], tout[siz[v]][to]));
}
}
if (!mult[siz[v]][v].empty()) {
if (sz(mult[siz[v]][v]) == 1) {
diam[siz[v]][v] = *mult[siz[v]][v].begin();
} else {
diam[siz[v]][v] = (*mult[siz[v]][v].begin()) + (*next(mult[siz[v]][v].begin()));
}
}
bestDiam.insert(diam[siz[v]][v]);
++siz[v];
for (auto [to, i] : g[v]) {
if (!used[to]) {
lst[i] = siz[v];
solve(centroid(to, sz[to], -1));
}
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, q;
ll WW;
cin >> n >> q >> WW;
ll last = 0;
for (int i = 0; i < n - 1; ++i) {
cin >> A[i] >> B[i] >> W[i];
--A[i], --B[i];
g[A[i]].emplace_back(B[i], i);
g[B[i]].emplace_back(A[i], i);
}
calc_sz(0, -1);
solve(centroid(0, n, -1));
assert(!bestDiam.empty());
while (q--) {
int i;
ll w;
cin >> i >> w;
i = (last + i) % (n - 1);
w = (w + last) % WW;
ll zz = w;
w = w - W[i];
W[i] = zz;
for (int j = 0; j < lst[i]; ++j) {
int root = Root[j][i];
int v = Child[j][i];
int p = Parent[j][i];
int pp = PP[j][i];
bestDiam.extract(diam[j][root]);
mult[j][root].extract(st[j][root].get(tin[j][pp], tout[j][pp]));
st[j][root].modify(tin[j][v], tout[j][v], w);
mult[j][root].insert(st[j][root].get(tin[j][pp], tout[j][pp]));
if (!mult[j][root].empty()) {
if (mult[j][root].size() == 1) {
diam[j][root] = *mult[j][root].begin();
} else {
diam[j][root] = (*mult[j][root].begin()) + (*next(mult[j][root].begin()));
}
}
bestDiam.insert(diam[j][root]);
}
assert(!bestDiam.empty());
last = *bestDiam.begin();
cout << last << '\n';
}
return 0;
}
