#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;;
#define ll long long
#define ar array
template<typename T>
using oset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define int long long
#define all(v) v.begin(), v.end()
#define ld long double
const int N = 4e5 + 20;
const int M = 2;
const int LOG = 20;
const ll INF = 1e17;
int MOD = 998244353;
// #pragma GCC target("avx2")
// #pragma GCC optimize("O3")
// //#pragma GCC optimize("unroll-loops")
template<typename T>
inline void chmin(T &x,T y){x = min(x, y);}
template<typename T>
inline void chmax(T &x,T y){x = max(x, y);}
inline void mm(int &x){x = (x % MOD + MOD) % MOD;};
struct Node{
int da;
int m2da;
int dam2dc;
int m2dcda;
int ans;
Node(){
da = m2da = dam2dc = m2dcda = ans = -INF;
}
Node(int x){
da = x;
m2da = - 2 * x;
dam2dc = -x;
m2dcda = -INF;
ans = -INF;
}
};
Node operator+(Node a, Node b){
Node res;
res.da = max(a.da, b.da);
res.m2da = max(a.m2da, b.m2da);
res.dam2dc = max({a.dam2dc, b.dam2dc, a.da + b.m2da});
res.m2dcda = max({a.m2dcda, b.m2dcda, a.m2da + b.da});
res.ans = max({a.ans, b.ans, a.dam2dc + b.da, a.da + b.m2dcda});
return res;
}
Node s[4 * N];
int lz[4 * N];
void bld(int k,int tl,int tr){
if(tl == tr){
s[k] = Node(0);
return;
}
int tm = (tl + tr) / 2;
bld(k * 2, tl, tm);
bld(k * 2 + 1, tm + 1, tr);
s[k] = s[k * 2] + s[k * 2 + 1];
}
void psh(int k,int tl,int tr){
s[k].da += lz[k];
s[k].m2da -= 2 * lz[k];
s[k].dam2dc -= lz[k];
s[k].m2dcda -= lz[k];
if(tl != tr){
lz[k * 2] += lz[k];
lz[k * 2 + 1] += lz[k];
}
lz[k] = 0;
}
void upd(int k,int tl,int tr, int l,int r,int v){
psh(k, tl, tr);
if(l > tr || tl > r)return;
if(l <= tl && tr <= r){
lz[k] += v;
psh(k, tl, tr);
return;
}
int tm = (tl + tr) / 2;
upd(k * 2, tl, tm, l, r, v);
upd(k * 2 + 1, tm + 1, tr, l, r, v);
s[k] = s[k * 2] + s[k * 2 +1];
}
int qry(){
psh(1, 0, 1);
return s[1].ans;
}
vector<ar<int,2>> g[N];
int da[N];
vector<int> ord;
int ind[N];
void dfs(int x,int p){
ord.push_back(x);
for(auto [u, w]: g[x]){
if(u == p)continue;
ind[w] = u;
dfs(u, x);
ord.push_back(x);
}
}
void orz(){
int n, q, w;
cin>>n>>q>>w;
int A[n - 1];
for(int i = 0;i < n - 1;i++){
int a, b, c;
cin>>a>>b>>c;
--a, --b;
A[i] = c;
g[a].push_back({b, i});
g[b].push_back({a, i});
}
dfs(0, 0);
int L[n], R[n];
memset(L, 0x3f, sizeof L);
memset(R, -0x3f, sizeof R);
int m = ord.size();
for(int i = 0;i < m;i++){
chmin(L[ord[i]], i);
chmax(R[ord[i]], i);
}
bld(1, 0, m - 1);
// assert(0);
for(int i = 0;i < n - 1;i++){
int x = ind[i];
upd(1, 0, m - 1, L[x], R[x], A[i]);
}
// cout<<qry()<<'\n';
int lst = 0;
while(q--){
int a, b;
cin>>a>>b;
a = (a + lst) % (n - 1);
b = (b + lst) % w;
int x = ind[a];
upd(1, 0, m - 1, L[x], R[x], -A[a]);
A[a] = b;
upd(1, 0, m - 1, L[x], R[x], +A[a]);
lst = qry();
cout<<lst<<'\n';
}
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int t = 1;
//cin>>t;
while (t--)orz();
}
//I am stupid :D
