#include<bits/stdc++.h>
#define forf(i,a,b) for(int i = a; i<=b; i++)
#define all(v) v.begin(),v.end()
using namespace std;
typedef long long ll;
int N,Q; ll W;
struct Seg{
vector<ll> arr,lazy;
void init(int siz){
forf(i,1,4*siz+1){
arr.push_back(0); lazy.push_back(0);
}
}
void propagate(int now, int s, int e){
if(lazy[now]){
arr[now] += lazy[now];
if(s!=e){ lazy[now*2+1] += lazy[now]; lazy[now*2] += lazy[now]; }
lazy[now] = 0;
}
}
void update(int now, int s, int e, int l, int r, ll v){
propagate(now,s,e);
if(l<=s && e<=r){
arr[now] += v;
if(s!=e){ lazy[now*2] += v; lazy[now*2+1] += v;}
return;
}
if(e<l || s>r) return;
int m = s+e>>1;
update(now*2,s,m,l,r,v); update(now*2+1,m+1,e,l,r,v);
arr[now] = max(arr[now*2],arr[now*2+1]);
}
ll query(int now, int s, int e, int l, int r){
propagate(now,s,e);
if(l<=s && e<=r) return arr[now];
if(e<l || s>r) return 0;
int m = s+e>>1;
return max(query(now*2,s,m,l,r),query(now*2+1,m+1,e,l,r));
}
} seg;
pair<int, int> edge[100001];
ll edgev[100001];
vector<int> adj[100001];
int in[100001], out[100001];
int sidecount,sidenum[100001], side[100001];
int ord;
void dfsord(int now, int p = -1, int s = -1){
in[now] = ++ord;
side[now] = s;
for(int i : adj[now]){
if(i==p)continue;
if(now == 1){
sidenum[++s] = i;
dfsord(i,now,s);
}
else dfsord(i,now,s);
}
sidecount = s;
out[now] = ord;
}
multiset<ll> ms;
ll sidemax[100001];
void upd(int now, ll delta){
seg.update(1,1,N,in[now],out[now],delta);
ms.erase(ms.find(-sidemax[side[now]]));
int tmp = sidenum[side[now]];
sidemax[side[now]] = seg.query(1,1,N,in[tmp],out[tmp]);
ms.insert(-sidemax[side[now]]);
}
ll ans(){
if(ms.size() == 1) return - *ms.begin();
else{
auto it = ms.begin();
ll ret = - *it;
it++; ret-=*it;
return ret;
}
}
int main(){
scanf("%d %d %lld" , &N, &Q,&W);
forf(i,0,N-2){
int u,v; scanf("%d %d %lld" , &u,&v,&edgev[i]);
edge[i] = {u,v};
adj[u].push_back(v); adj[v].push_back(u);
}
dfsord(1);
seg.init(N);
forf(i,0,sidecount) ms.insert(0);
forf(i,0,N-2){
int now = edge[i].first;
if(in[edge[i].second] > in[edge[i].first]) now = edge[i].second;
upd(now,edgev[i]);
}
ll last = 0;
while(Q--){
int x; ll v; scanf("%d %lld" , &x,&v);
x+=last; x%=(N-1);
v+=last; v%=W;
int now = edge[x].first;
if(in[edge[x].second] > in[edge[x].first]) now = edge[x].second;
ll delta = v-edgev[x];
edgev[x] = v;
upd(now,delta);
last = ans();
printf("%lld\n" , last);
}
}
