#include <algorithm>
#include <iostream>
#include <unordered_map>
#include <vector>
using namespace std;
#define endl "\n"
#define ll long long
const int MOD = 1e9 + 7;
const int mx = 1e5 + 10;
unordered_map<ll, ll> cost[mx];
vector<ll> tree[mx];
ll ans = 0;
ll dfs(ll node, vector<bool> &vis) {
vis[node] = 1;
ll one = -1, second = -1;
for (ll nex : tree[node]) {
if (vis[nex] == 0) {
ll val = cost[node][nex] + dfs(nex, vis);
if (val >= one) {
second = one;
one = val;
} else if (val > second) {
second = val;
}
}
}
if (one == -1 && second == -1) {
return 0;
} else if (second == -1) {
ans = max(ans, one);
} else {
ans = max(ans, one + second);
}
return one;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
ll n, q, w;
cin >> n >> q >> w;
vector<pair<ll, ll>> arr(n);
for (int i = 0; i < n - 1; i++) {
int a, b, c;
cin >> a >> b >> c;
tree[a].push_back(b);
tree[b].push_back(a);
cost[a][b] = c;
cost[b][a] = c;
arr[i] = {a, b};
}
ll last = 0;
while (q--) {
ll d, e;
cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
pair<ll, ll> c = arr[d];
cost[c.first][c.second] = e;
cost[c.second][c.first] = e;
// dp method
// build up from root nodes of tree
vector<bool> vis(n + 1, 0);
ans = 0;
dfs(1, vis);
last = ans;
cout << ans << endl;
}
return 0;
}
// what if its star?
// does it make any difference?
