#include <bits/stdc++.h>
using namespace std;
#define int long long
#define all(x) x.begin(), x.end()
#define size(x) (int)x.size()
template<class S, class T>
bool chmin(S &a, const T &b) {
return a > b ? (a = b) == b : false;
}
template<class S, class T>
bool chmax(S &a, const T &b) {
return a < b ? (a = b) == b : false;
}
signed main() {
cin.tie(nullptr)->sync_with_stdio(false);
int n, q, w;
cin >> n >> q >> w;
int a[n], b[n], c[n];
vector<pair<int, int>> g[n + 1];
for (int i = 1; i < n; ++i) {
cin >> a[i] >> b[i] >> c[i];
g[a[i]].push_back({b[i], i});
g[b[i]].push_back({a[i], i});
}
if (n <= 5000 && q <= 5000) {
vector<vector<int>> dp(n + 1, vector<int> (3, 0));
function<void(int, int)> dfs = [&](int v, int p) {
dp[v][0] = dp[v][1] = dp[v][2] = 0;
int max1 = 0, max2 = 0;
for (auto [to, idx] : g[v]) {
int cost = c[idx];
if (to != p) {
dfs(to, v);
chmax(dp[v][0], dp[to][0]);
chmax(dp[v][0], dp[to][1] + cost);
chmax(dp[v][0], dp[to][2]);
chmax(dp[v][1], dp[to][1] + cost);
if (max1 < dp[to][1] + cost) {
chmax(max2, max1);
max1 = dp[to][1] + cost;
} else chmax(max2, dp[to][1] + cost);
}
}
dp[v][2] = max1 + max2;
};
int last = 0;
while (q--) {
int d, e; cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
d++;
c[d] = e;
dfs(1, -1);
last = max({dp[1][0], dp[1][1], dp[1][2]});
cout << last << '\n';
}
} else if (size(g[1]) == n - 1) {
multiset<int> st;
for (int i = 1; i < n; ++i) {
st.insert(c[i]);
}
int last = 0;
while (q--) {
int d, e; cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
d++;
st.erase(st.find(c[d]));
st.insert(e);
c[d] = e;
if (size(st) == 1) {
last = *st.rbegin();
} else {
int v = *st.rbegin();
st.erase(--st.end());
last = v + *st.rbegin();
st.insert(v);
}
cout << last << '\n';
}
} else {
vector<int> parent(n + 1, -1);
function<void(int, int)> count_parents = [&](int v, int p) {
parent[v] = p;
for (auto [to, idx] : g[v]) {
if (to != p) {
count_parents(to, v);
}
}
};
count_parents(1, -1);
vector<vector<int>> dp(n + 1, vector<int> (3, 0));
function<void(int, int)> count_dp = [&](int v, int p) {
dp[v][0] = dp[v][1] = dp[v][2] = 0;
int max1 = 0, max2 = 0;
for (auto [to, idx] : g[v]) {
int cost = c[idx];
if (to != p) {
count_dp(to, v);
chmax(dp[v][0], dp[to][0]);
chmax(dp[v][0], dp[to][1] + cost);
chmax(dp[v][0], dp[to][2]);
chmax(dp[v][1], dp[to][1] + cost);
if (max1 < dp[to][1] + cost) {
chmax(max2, max1);
max1 = dp[to][1] + cost;
} else chmax(max2, dp[to][1] + cost);
}
}
dp[v][2] = max1 + max2;
};
count_dp(1, -1);
function<void(int)> upd = [&](int v) {
if (v == -1) return;
dp[v][0] = dp[v][1] = dp[v][2] = 0;
int max1 = 0, max2 = 0;
for (auto [to, idx] : g[v]) {
int cost = c[idx];
if (to != parent[v]) {
chmax(dp[v][0], dp[to][0]);
chmax(dp[v][0], dp[to][1] + cost);
chmax(dp[v][0], dp[to][2]);
chmax(dp[v][1], dp[to][1] + cost);
if (max1 < dp[to][1] + cost) {
chmax(max2, max1);
max1 = dp[to][1] + cost;
} else chmax(max2, dp[to][1] + cost);
}
}
dp[v][2] = max1 + max2;
upd(parent[v]);
};
int last = 0;
while (q--) {
int d, e; cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
d++;
c[d] = e;
if (parent[a[d]] == b[d]) upd(b[d]);
else upd(a[d]);
last = max({dp[1][0], dp[1][1], dp[1][2]});
cout << last << '\n';
}
}
}
