// ~Be name khoda~ //
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define pb push_back
#define mp make_pair
#define all(x) x.begin(), x.end()
#define fi first
#define se second
const int maxn = 1e6 + 10;
const int maxn5 = 5e5 + 10;
const int maxnt = 1.2e6 + 10;
const int maxn3 = 1e3 + 10;
const int mod = 1e9 + 7;
const ll inf = 1e18;
ll h[maxn5], c[maxn5];
vector <pair<int, ll>> adj[maxn5];
int a[maxn5], b[maxn5];
inline void dfs(int v, int par){
for(auto [u, id] : adj[v]) if(u != par){
h[u] = h[v] + c[id];
dfs(u, v);
}
return;
}
int main()
{
ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
ll w;
int n, q; cin >> n >> q >> w;
for(int i = 0; i < n - 1; i++){
cin >> a[i] >> b[i] >> c[i];
a[i]--; b[i]--;
adj[a[i]].pb({b[i], i});
adj[b[i]].pb({a[i], i});
}
ll last = 0;
for(int i = 0; i < q; i++){
ll d, e; cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
c[d] = e;
h[0] = 0;
dfs(0, -1);
int di = 0;
for(int i = 0; i < n; i++) if(h[i] >= h[di])
di = i;
h[di] = 0;
dfs(di, -1);
last = 0;
for(int i = 0; i < n; i++)
last = max(last, h[i]);
cout << last << '\n';
}
}
