#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define all(x) (x).begin(),(x).end()
#define pb push_back
#define fi first
#define se second
#define beg begin
#define siz size()
#define fastio cin.tie(NULL); cout.tie(NULL); ios_base::sync_with_stdio(false);
#define endl '\n'
#define ins insert
#define log LOG
const ll inf = 1e9;
const ll mod = 10289;
const int maxn=5002;
const int log=24;
int n,q,vis[maxn],dis[maxn],w,mx;
vector<int>adj[maxn];
ll x[maxn][maxn];
vector<pii>ed;
void dfs(int v,int p){
for(auto u:adj[v]){
if(p==u)continue;
dis[u]=dis[v]+x[u][v];
dfs(u,v);
}
if(dis[v]>dis[mx])mx=v;
}
int main(){
fastio
cin>>n>>q>>w;
for(int i=1;i<n;i++){
ll a,b,c;
cin>>a>>b>>c;
x[a][b]=c;
x[b][a]=c;
ed.pb({a,b});
adj[a].pb(b);adj[b].pb(a);
}
int ld=0;
while(q--){
ll d,e;
cin>>d>>e;d+=ld;e+=ld;d%=(n-1);e%=w;
ll u=ed[d].fi,v=ed[d].se;
x[u][v]=e;x[v][u]=e;
mx=0;dis[1]=0;
dfs(1,-1);
dis[mx]=0;
dfs(mx,-1);
cout<<dis[mx]<<endl;
ld=dis[mx];
}
}
