/*
in the name of god
*/
//#pragma GCC optimize("Ofast,O3,unroll-loops")
//#pragma GCC target("avx,avx2,fma")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4.1,sse4.2,sse4a,avx,avx2,popcnt,tune=native")
#include <bits/stdc++.h>
using namespace std;
#define int long long
typedef pair<int,int> pii;
typedef pair<long long ,long long> pll;
typedef long long ll ;
#define File freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout);
#define all(V) V.begin(),V.end()
#define setprec(x) fixed << setprecision(x)
#define Mp(a,b) make_pair(a,b)
#define len(V) (int)(V.size())
#define sep ' '
#define endl '\n'
#define pb(x) push_back(x)
#define fi first
#define sec second
#define popcount(x) __builtin_popcount(x)
#define lid u<<1
#define rid (lid)|1
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
const ll N = 1e5 + 10,SQ=320,LOG=21;
const ll inf = 2e18 + 10 , MD = 1e9 + 7;
inline ll md(ll x){ x %= MD; return (x < 0 ? x + MD : x);}
int n , q;
int sz[N];
bool mark[N];
int par[N];
int comp[LOG][N];
int dis[LOG][N];
int lev[N];
int val[N];
vector<pii> g[N];
int mn[N];
set<pii> st[N];
vector<int> ver[N];
int ind[LOG][N],ind2[LOG][N];
vector<int> E[N];
map<pii,int> mp;
int tim[LOG];
int dfs_sz(int u,int p){
sz[u] = 1;
for(auto h : g[u]){
if(h.fi!=p and !mark[h.fi]) sz[u] += dfs_sz(h.fi,u);
}
return sz[u];
}
int centroid(int u,int p,int S){
for(auto h : g[u]){
if(h.fi!=p and !mark[h.fi] and sz[h.fi] > S/2) return centroid(h.fi,u,S);
}
return u;
}
void dfs(int u,int p,int l,int w,int r){
comp[l][u] = r;
dis[l][u] = w;
ind[l][u] = tim[l]++;
ind[l][u]++;
ver[l].pb(u);
int I = mp[Mp(min(u,p),max(u,p))];
E[I].pb(l);
for(auto h : g[u]){
if(h.fi!=p and !mark[h.fi]) dfs(h.fi,u,l,w + h.sec,r);
}
ind2[l][u] = tim[l];
ind2[l][u]++;
}
int dec(int u,int l){
int c = centroid(u,u,dfs_sz(u,u));
mark[c] = 1;
lev[c] = l;
dis[l][c] = 0;
ver[l].pb(c);
ind[l][c] = (tim[l]++);
ind[l][c]++;
for(auto h : g[c]){
if(!mark[h.fi]){
dfs(h.fi,c,l,h.sec,h.fi);
}
}
ind2[l][c] = tim[l];
ind2[l][c]++;
for(auto h : g[c]){
if(!mark[h.fi]) par[dec(h.fi,l+1)] = c;
}
return c;
}
struct node{
pii mx;
int lazy=1;
node(pii a,int l){mx = a,lazy = l;}
node(){}
};
struct SEG{
node seg[N<<2];
node khon = node({-inf,-1},0);
node merge(const node& a,const node& b){
return node(max(a.mx,b.mx),0);
}
void shift(int u,int l,int r,int x){
seg[u].mx.fi += x;
seg[u].lazy += x;
}
void relax(int u,int l,int r){
int mid = (l+r)>>1;
shift(lid,l,mid,seg[u].lazy);
shift(rid,mid,r,seg[u].lazy);
seg[u].lazy = 0;
}
void build(int u=1,int l=1,int r=n+1){
if(r-l==1){
seg[u].mx = {-inf,l};
seg[u].lazy = 0;
return ;
}
int mid = (l+r)>>1;
build(lid,l,mid);
build(rid,mid,r);
seg[u] = merge(seg[lid],seg[rid]);
}
void update(int s,int e,int v,int u=1,int l=1,int r=n+1){
if(e <= l || e <= l || r <= s) return ;
if(s <= l and r <= e){
shift(u,l,r,v);
return ;
}
int mid = (l+r)>>1;
relax(u,l,r);
update(s,e,v,lid,l,mid);
update(s,e,v,rid,mid,r);
seg[u] = merge(seg[lid],seg[rid]);
}
node get(int s,int e,int u=1,int l=1,int r=n+1){
if(e <= s) return khon;
if(s <= l and r <= e) return seg[u];
int mid = (l+r)>>1;
relax(u,l,r);
if(e <= mid) return get(s,e,lid,l,mid);
if(s >= mid) return get(s,e,rid,mid,r);
return merge(get(s,e,lid,l,mid), get(s,e,rid,mid,r));
}
} se[LOG];
vector<int> wei;
vector<pii> arr;
void change(int j,int w){
int dif = -wei[j] + w;
wei[j] = w;
for(auto h : E[j]){
int u = arr[j].fi,v= arr[j].sec;
if(ind[h][u] > ind[h][v]) swap(u,v);
se[h].update(ind[h][v],ind2[h][v],dif);
}
}
pii ask(int v){
pii ans = se[lev[v]].get(ind[lev[v]][v],ind2[lev[v]][v]).mx;
int u = v;
int lst = v;
v = par[v];
while(v){
int tmp = se[lev[v]].get(ind[lev[v]][u],ind[lev[v]][u]+1).mx.fi;
int c = comp[lev[v]][lst];
pii s1 = {ind[lev[v]][v],ind2[lev[v]][v]};
pii s2 = {ind[lev[v]][c],ind2[lev[v]][c]};
if(!c) assert(0);
if(s1.fi == 0 or s2.fi == 0 or s2.sec == 0 or s1.sec == 0) assert(0);
pii tmp2 = max(se[lev[v]].get(s1.fi,s2.fi).mx,se[lev[v]].get(s2.sec,s1.sec).mx);
if(tmp2.fi < 0) assert(0);
tmp2.fi += tmp;
tmp2.sec = ver[lev[v]][tmp2.sec - 1];
ans = max(ans,tmp2);
lst = v;
v = par[v];
}
return ans;
}
int32_t main() {
ios_base::sync_with_stdio(false);cout.tie(0);cin.tie(0);
int W ;
cin >> n >> q >> W;
for(int i = 0 ; i < n -1;i++){
int u,v,w;
cin >> u >> v >> w;
wei.pb(w);
arr.pb(Mp(min(u,v),max(u,v)));
mp[Mp(min(u,v),max(u,v))] = i;
g[u].pb(Mp(v,w));
g[v].pb(Mp(u,w));
}
dec(1,0);
for(int i = 0 ; i < LOG;i++) se[i].build();
for(int i =1 ;i <= n;i++){
int v = i;
while(v){
se[lev[v]].update(ind[lev[v]][i],ind[lev[v]][i]+1,inf + dis[lev[v]][i]);
v = par[v];
}
}
int last = 0;
while(q--){
int e,w;
cin >> e >> w;
e = (e + last)%(n-1);
w = (w+last)%W;
change(e,w);
last = ask(ask(1).sec).fi;
cout << last << endl;
}
return 0;
}
