#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define f1 first
#define s2 second
using ii = pair<int, int>;
using ll = long long;
const int MAX = 5069;
int N, Q, W;
int len[MAX];
vector<ii> adj[MAX];
ll depth[MAX];
inline ll getdia()
{
const auto dfs = [&](const auto &self, int node, int par) -> void
{
for (auto [to, id] : adj[node]) if (to != par)
{
depth[to] = depth[node] + len[id];
self(self, to, node);
}
};
depth[1] = 0;
dfs(dfs, 1, -1);
int best = 1;
for (int i = 2; i <= N; ++i)
if (depth[best] < depth[i])
best = i;
depth[best] = 0;
dfs(dfs, best, -1);
return *max_element(depth+1, depth+N+1);
}
int main()
{
ios :: sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> N >> Q >> W;
for (int i = 0, u, v; i < N-1; ++i)
{
cin >> u >> v >> len[i];
adj[u].pb({v, i});
adj[v].pb({u, i});
}
for (int prv = 0, i, x; Q--;)
{
cin >> i >> x;
(i += prv) %= (N-1);
(x += prv) %= W;
// cerr << i << " and " << x << '\n';
len[i] = x;
cout << (prv = getdia()) << '\n';
}
return 0;
}
