#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[100001];
pair<int, int> edge[100001];
ll edgev[100001];
vector<int> adj[100001];
int CENT;
//cent
int chk[100001];
int sz[100001];
int par[100001] , d[100001] , siz[100001];
vector<int> son[100001] ,soncent[100001];
int getsz(int now, int p = -1){
sz[now] = 1;
for(int &i : adj[now]) if(i!=p && !chk[i]) sz[now] += getsz(i,now);
return sz[now];
}
int getcent(int now, int cap, int p = -1){
for(int &i : adj[now]) if(i!=p && !chk[i] && 2*sz[i] > cap) return getcent(i,cap,now);
return now;
}
int centdecom(int now, int p = -1 ,int dep = 0){
int cent = getcent(now,getsz(now));
par[cent] = p; d[cent] = dep; chk[cent] = 1; siz[cent] = sz[now];
for(int &i : adj[cent]){
if(chk[i]) continue;
int there = centdecom(i,cent,dep+1);
son[cent].push_back(i);
soncent[cent].push_back(there);
}
return cent;
}
//ett
int in[20][100001], out[20][100001];
int sidecount[100001];
int side[20][100001];
vector<ll> sidemax[100001];
int ord;
void dfsord(int st ,int now, int dep, int p = -1, int s = -1){
in[dep][now] = ++ord;
side[dep][now] = s;
for(int i : adj[now]){
if(i==p || d[i] < dep) continue;
if(now == st) dfsord(st,i,dep,now,++s);
else dfsord(st,i,dep,now,s);
}
sidecount[st] = s;
out[dep][now] = ord;
}
multiset<ll> ms[100001];
multiset<ll> ansset;
void init(){
CENT = centdecom(1);
forf(i,1,N){
seg[i].init(siz[i]);
ord= 0;
dfsord(i,i,d[i]);
forf(j,0,sidecount[i]) ms[i].insert(0);
ansset.insert(0);
sidemax[i].resize(sidecount[i]+1,0);
}
}
ll ans = 0;
ll ansv(int now){
if (ms[now].size() == 1) return *ms[now].begin();
else {
auto it = ms[now].begin();
ll ret = *it;
it++; ret += *it;
return ret;
}
}
void upd(int now1, int now2, ll delta){
int nowd = 0;
int nowc = CENT;
while(siz[nowc] > 1) {
if(min(d[now1],d[now2]) < nowd) break;
int now = now1;
if(in[nowd][now2] > in[nowd][now1]) now = now2;
seg[nowc].update(1, 1, siz[nowc], in[nowd][now], out[nowd][now], delta);
int s = side[nowd][now];
int tmp = son[nowc][s];
ansset.erase(ansset.find(ansv(nowc)));
ms[nowc].erase(ms[nowc].find(-sidemax[nowc][s]));
sidemax[nowc][s] = seg[nowc].query(1, 1, siz[nowc], in[nowd][tmp], out[nowd][tmp]);
ms[nowc].insert(-sidemax[nowc][s]);
ansset.insert(ansv(nowc));
nowc = soncent[nowc][s];
nowd++;
}
int trash = 0;
}
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);
}
init();
forf(i,0,N-2){
upd(edge[i].first, edge[i].second,edgev[i]);
}
ll last = 0;
while(Q--){
ll x; ll v; scanf("%lld %lld" , &x,&v);
x+=last; x%=(N-1);
v+=last; v%=W;
ll delta = v-edgev[x];
edgev[x] = v;
upd(edge[x].first,edge[x].second,delta);
ans = - *ansset.begin();
last = ans;
printf("%lld\n" , last);
}
}
