#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ff first
#define ss second
#define rep(i,s,f) for(int i = s;i < f;i++)
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define pb push_back
const int N = 1e5 + 1;
set<pair<int,int>> g[N];
int mx,fnd;
void dfs(int n,int p,int dis,bool check){
if(dis > mx){
mx = dis;
fnd = n;
}
for(auto [to,cost] : g[n]){
if(to != p){
dfs(to,n,dis + cost,check);
}
}
}
void solve(){
int n,m,w;
cin >> n >> m >> w;
array<int,3> ind[n];
for(int i = 0;i < n - 1;i++){
int a,b,c;
cin >> a >> b >> c;
g[a].insert({b,c});
g[b].insert({a,c});
ind[i] = {a,b,c};
}
int last = 0;
for(int i = 0;i < m;i++){
int d,e;
cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
auto &[a,b,c] = ind[d];
g[a].erase({b,c});
g[b].erase({a,c});
g[a].insert({b,e});
g[b].insert({a,e});
ind[d][2] = e;
if(n <= 5000 && m <= 5000){
dfs(1,-1,0,0);
dfs(fnd,-1,0,1);
cout << mx << "\n";
last = mx;
mx = 0;
}
}
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0),cout.tie(0);
int t = 1;
//~ cin >> t;
while(t--){
solve();
}
}
