#include <array>
#include <iostream>
#include <vector>
using namespace std;
int n, q;
long long W;
vector<array<long long, 3>> edges;
vector<vector<int>> adj;
void update(int k, long long e){
auto& [a, b, w] = edges[k];
w = e;
}
long long get_answer(){
long long ans = 0;
for (int i = 0; i < n; i++){
auto dfs = [&](auto&& dfs, int v, int p, long long d) -> void {
ans = max(ans, d);
for (int idx : adj[v]){
auto [a, b, w] = edges[idx];
int x = a + b - v;
if (x != p)
dfs(dfs, x, v, d + w);
}
};
dfs(dfs, i, -1, 0);
}
return ans;
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin >> n >> q >> W;
adj.resize(n);
long long a, b, c;
for (int i = 0; i < n-1; i++){
cin >> a >> b >> c;
--a, --b;
adj[a].push_back(i);
adj[b].push_back(i);
edges.push_back({a, b, c});
}
long long last = 0;
long long d, e;
while (q--){
cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % W;
update(d, e);
last = get_answer();
cout << last << "\n";
}
return 0;
}
