#include <bits/stdc++.h>
#define int long long
using namespace std;
const int maxn = 200005;
const int INF = (int)1e16;
int a,q,sadge;
vector<pair<int,int>> z[maxn];
int high[maxn];
int sta[maxn], fin[maxn], euler[3*maxn], tour=0;
int depth[1000005];
int par[300001][21];
bool cmp(pair<int,int> a,pair<int,int> b){
return a.second<b.second;
}
void dfs(int u, int p){
sta[u] = ++tour;
par[u][0]=p;
euler[tour] = u;
for(auto &pr: z[u]){
int v = pr.first, w = pr.second;
if(v==p) continue;
high[v] = high[u] + w;
depth[v]=depth[u]+1;
dfs(v, u);
euler[++tour] = u;
}
fin[u] = ++tour;
euler[tour] = u;
}
int lca1(int x,int y){
for (int i=20;i>=0;i--){
if (depth[par[x][i]]>depth[y]){
x=par[x][i];
}
}
return x;
}
int lca(int x,int y){
if (depth[x]<depth[y]){
swap(x,y);
}
for (int i=20;i>=0;i--){
if (depth[par[x][i]]>=depth[y]){
x=par[x][i];
}
}
if (x==y){
return x;
}
for (int i=20;i>=0;i--){
if (par[x][i]!=par[y][i] && par[x][i]!=0){
x=par[x][i];
y=par[y][i];
}
}
return par[x][0];
}
struct node {
int max1, min1, lazy;
int val, val1;
};
node f[12*maxn];
node combine(const node &A, const node &B){
node R;
R.max1 = max(A.max1, B.max1);
R.min1 = min(A.min1, B.min1);
R.lazy = 0;
R.val = max({ A.val, B.val, B.max1 - 2*A.min1 });
R.val1 = max({ A.val1, B.val1, A.max1 - 2*B.min1 });
return R;
}
void push(int id){
if(f[id].lazy){
int d = f[id].lazy;
for(int ch: {id*2, id*2+1}){
f[ch].lazy += d;
f[ch].max1 += d;
f[ch].min1 += d;
f[ch].val -= d;
f[ch].val1 -= d;
}
f[id].lazy = 0;
}
}
void build(int id, int l, int r){
if(l==r){
int h = high[euler[l]];
f[id].max1 = f[id].min1 = h;
f[id].lazy = 0;
f[id].val = -INF;
f[id].val1 = -INF;
return;
}
int m = (l+r)/2;
build(id*2, l, m);
build(id*2+1, m+1, r);
f[id] = combine(f[id*2], f[id*2+1]);
}
void update(int id, int l, int r, int x, int y, int d){
if(y<l || x>r) return;
if(x<=l && r<=y){
f[id].max1 += d;
f[id].min1 += d;
f[id].lazy += d;
f[id].val -= d;
f[id].val1 -= d;
return;
}
push(id);
int m = (l+r)/2;
update(id*2, l, m, x, y, d);
update(id*2+1, m+1, r, x, y, d);
f[id] = combine(f[id*2], f[id*2+1]);
}
node get(int id, int l, int r, int x, int y){
if(y<l || x>r){
return { -INF, INF, 0, -INF, -INF };
}
if(x<=l && r<=y){
return f[id];
}
push(id);
int m = (l+r)/2;
return combine(
get(id*2, l, m, x, y),
get(id*2+1, m+1, r, x, y)
);
}
int get1(int id,int l,int r,int pos){
if (l==r){
return f[id].max1;
}
int mid=(l+r)/2;
push(id);
if (pos<=mid){
return get1(id*2,l,mid,pos);
}else{
return get1(id*2+1,mid+1,r,pos);
}
}
int get2(int id,int l,int r,int val){
if (l==r){
return l;
}
int mid=(l+r)/2;
push(id);
if (f[id*2].max1==val){
return get2(id*2,l,mid,val);
}else{
return get2(id*2+1,mid+1,r,val);
}
}
struct node1{
int x,y,t;
};
node1 edge[1000005];
vector <pair<int,int>> segment;
vector <pair<int,int>> v;
signed main(){
ios::sync_with_stdio(false);
cin.tie(NULL);
cin >> a >> q >> sadge;
for(int i=1;i<a;i++){
int x,y,t;
cin >> x >> y >> t;
z[x].push_back({y,t});
z[y].push_back({x,t});
edge[i]={x,y,t};
}
depth[0]=-1;
dfs(1,0);
build(1,1,tour);
for (int i=1;i<a;i++){
if (depth[edge[i].x]<depth[edge[i].y]){
swap(edge[i].x,edge[i].y);
}
}
for (int j=1;j<=20;j++){
for (int i=1;i<=a;i++){
par[i][j]=par[par[i][j-1]][j-1];
}
}
// cout << tour << "\n";
int cnt=0;
int last=0;
while(q--){
int x,y;
cin >> x >> y;
x=(last+x)%(a-1);
y=(last+y)%sadge;
// cout << x << " " << y << "\n";
x++;
int cur=edge[x].t;
int diff=y-cur;
int v=edge[x].x;
edge[x].t=y;
update(1,1,tour,sta[v],fin[v],diff);
int maxlen=f[1].max1;
int pos=get2(1,1,tour,maxlen);
int res=get(1,1,tour,1,pos).val1;
int res1=get(1,1,tour,pos,tour).val;
cout << max(res,res1)+maxlen << "\n";
last=max(res,res1)+maxlen;
}
return 0;
}
/*
5
1 2 1
1 4 2
2 3 3
2 5 4
2
2 1 100
1 2 4 1 3 4 5
*/
