#include<algorithm>
#include<iostream>
#include<cassert>
#include<vector>
#include<string>
#include<array>
#include<stack>
#include<queue>
#include<map>
#include<set>
using namespace std;
#define V vector
#define Int long long
#define rep(i,a,b) for(int i=(int)(a); i<(int)(b); i++)
#define nl '\n'
#define dbg(x) cout << "?" << #x << " : " << x << endl;
#define all(x) (x).begin(), (x).end()
#define int long long
#define pii pair<int,int>
const int N = 1e5+5;
int n, q, wlim;
V<array<int,3>> edges;
V<pair<int,int>> queries;
struct Sub1{
V<int> adj[N];
int mxdist = 0, mxnode = -1;
void dfs(int x,int par=-1,int dist=0){
if(dist >= mxdist){
mxdist = dist;
mxnode = x;
}
for(int id : adj[x]){
int y = edges[id][0]^edges[id][1]^x;
int w = edges[id][2];
if(y==par) continue;
dfs(y,x, dist+w);
}
}
void run(){
rep(i,0,n-1){
auto[u,v,w] = edges[i];
adj[u].push_back(i);
adj[v].push_back(i);
}
int last = 0;
for(auto[i,w] : queries){
i = (i+last)%(n-1);
w = (w+last)%wlim;
edges[i][2] = w;
mxdist = 0;
dfs(1);
dfs(mxnode);
cout << mxdist << nl;
last = mxdist;
}
}
};
struct Sub3{
int arr[N];
multiset<int> s;
void run(){
rep(i,0,n-1){
auto[u,v,w] = edges[i];
u = u^v^1;
arr[u] = w;
s.insert(w);
}
int last = 0;
for(auto[i,w] : queries){
i = (i+last)%(n-1);
w = (w+last)%wlim;
s.erase(s.find(arr[i]));
arr[i] = w;
s.insert(w);
int ans = *prev(s.end());
if(s.size() >= 2){
ans += *prev(prev(s.end()));
}
cout << ans << nl;
last = ans;
}
}
};
signed main(){
cin >> n >> q >> wlim;
rep(i,0,n-1){
int u, v, w;
cin >> u >> v >> w;
edges.push_back({u,v,w});
}
rep(i,0,q){
int idx, w;
cin >> idx >> w;
queries.push_back({idx,w});
}
bool sub3 = 1;
rep(i,0,n-1){
auto[u,v,w] = edges[i];
sub3 &= (u==1 || v==1);
}
if(sub3){
Sub3 sub; sub.run(); return 0;
}
Sub1 sub; sub.run(); return 0;
}
