#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 = 8e5+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;
}
ll seg[4*N],lz[4*N];
ll h[N];
ll e[N];
pll a[N];
int par[N][20],T,tin[N],tout[N],b[N],l[N];
vector<pair<int,ll>> adj[N];
void dfs(int v,int p){
par[v][0] = p;
tin[v] = T;
b[T] = v;
T++;
for (auto u : adj[v]){
if (u.X == p) continue;
h[u.X] = u.Y+h[v];
l[u.X] = l[v]+1;
dfs(u.X,v);
}
tout[v] = T;
b[T] = v;
T++;
}
void build(int l,int r,int v){
if (r-l == 1){
seg[v] = h[b[l]];
return;
}
int m = (l+r) >> 1,u = (v << 1);
build(l,m,u);
build(m,r,u|1);
seg[v] = max(seg[u],seg[u|1]);
}
void upd(int l,int r,int s,int e,ll x,int v = 1){
if (l >= s && e >= r){
seg[v] += x;
lz[v] += x;
return;
}
if (l >= e || s >= r) return;
int m = (l+r) >> 1,u = (v << 1);
if (lz[v]){
lz[u] += lz[v];
lz[u|1] += lz[v];
seg[u] += lz[v];
seg[u|1] += lz[v];
lz[v] = 0;
}
upd(l,m,s,e,x,u);
upd(m,r,s,e,x,u|1);
seg[v] = max(seg[u],seg[u|1]);
}
ll que(int l,int r,int s,int e,int v = 1){
if (l >= s && e >= r)
return seg[v];
if (l >= e || s >= r) return 0;
int m = (l+r) >> 1,u = (v << 1);
if (lz[v]){
lz[u] += lz[v];
lz[u|1] += lz[v];
seg[u] += lz[v];
seg[u|1] += lz[v];
lz[v] = 0;
}
return max(que(l,m,s,e,u),que(m,r,s,e,u|1));
}
inline int getpar(int v,int k){
repr(i,19,0){
if (k >= (1 << i)){
k -= (1 << i);
v = par[v][i];
}
}
return v;
}
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;
a[i] = {u,v};
adj[u].pb({v,d});
adj[v].pb({u,d});
}
dfs(1,0);
rep(i,0,n-1) if (par[a[i].X][0] == a[i].Y) swap(a[i].X,a[i].Y);
rep(j,1,20)
rep(i,2,n+1)
par[i][j] = par[par[i][j-1]][j-1];
ll last = 0;
build(0,T,1);
multiset<ll> st;
for (pll u : adj[1])
st.insert(que(0,T,tin[u.X],tout[u.X]+1));
while (q--){
int d;
ll x;
cin >> d >> x;
d = (d+last)%(n-1);
x = (x+last)%w;
ll y = a[d].Y;
int v = getpar(y,l[y]-1);
st.erase(st.find(que(0,T,tin[v],tout[v]+1)));
upd(0,T,tin[y],tout[y]+1,x-e[d]);
st.insert(que(0,T,tin[v],tout[v]+1));
e[d] = x;
auto it = st.rbegin();
last = (*it);
y = last;
st.erase(st.find(last));
if (st.empty()){
cout << last << endl;
st.insert(y);
continue;
}
it = st.rbegin();
last += (*it);
st.insert(y);
cout << last << endl;
}
}
