#include <bits/stdc++.h>
#pragma GCC optimize("O3,no-stack-protector,unroll-loops")
#pragma GCC target("avx2,fma")
#define rep(i,l,r) for (int i = l; i < r; i++)
#define repr(i,r,l) for (int i = r; i >= l; i--)
#define X first
#define Y second
#define pb push_back
#define endl '\n'
#define debug(x) cerr << #x << " : " << x << endl;
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pll;
typedef pair<long double,long double> pld;
const long long int N = 1e5+10,mod = 1e9+7,inf = 1e9,sq = 700,sig = 26;
inline int mkay(int a,int b){
if (a+b >= mod) return a+b-mod;
if (a+b < 0) return a+b+mod;
return a+b;
}
inline int poww(int n,int k){
int c = 1;
while (k){
if (k&1) c = (1ll*c*n)%mod;
n = (1ll*n*n)%mod;
k >>= 1;
}
return c;
}
vector<pll> adj[N];
ll e[N];
ll h[N];
int dfs(int v,int p){
ll mx = h[v];
int w = v;
for (pll u : adj[v]){
if(u.X == p) continue;
h[u.X] = h[v]+e[u.Y];
int x = dfs(u.X,v);
if (h[x] > mx){
mx = h[x];
w = x;
}
}
return w;
}
int main(){
ios :: sync_with_stdio(0); cin.tie(0);cout.tie(0);
int n,q;
ll w;
cin >> n >> q >> w;
rep(i,0,n-1){
int u,v;
ll d;
cin >> u >> v >> d;
e[i] = d;
adj[u].pb({v,i});
adj[v].pb({u,i});
}
ll last = 0;
while (q--){
int d;
ll x;
cin >> d >> x;
d = (d+last)%(n-1);
x = (x+last)%w;
e[d] = x;
h[1] = 0;
int u = dfs(1,-1);
h[u] = 0;
int v = dfs(u,-1);
cout << h[v] << endl;
last = h[v];
}
return 0;
}
