#include "bits/stdc++.h"
using namespace std;
const int LIM = 100000;
#define fi first
#define se second
typedef long long LL;
typedef pair<LL,LL> PLL;
namespace DynamicDiameter {
vector <PLL> edge[LIM + 5];
int event[2 * LIM + 5];
int dfsTime = 0;
LL weights[LIM + 5], depth[LIM + 5];
PLL order[LIM + 5];
void eulerTour(int pos, int par = -1) {
dfsTime++;
order[pos].fi = dfsTime;
event[dfsTime] = pos;
for (auto &nx: edge[pos]) {
if (nx.fi == par) continue;
depth[nx.fi] = depth[pos] + nx.se;
weights[nx.fi] = nx.se;
eulerTour(nx.fi, pos);
dfsTime++;
event[dfsTime] = pos;
}
order[pos].se = dfsTime;
return;
}
const LL INF = 1e14;
// Segment Tree starts here
struct Node{
LL maxDepth = -INF, minDepth = INF;
LL leftMax = -INF, rightMax = -INF;
LL diameter = 0;
LL lazy;
};
Node segt[8 * LIM + 5];
void pushDown(int rangeL = 1, int rangeR = dfsTime, int idx = 1){
if(segt[idx].lazy == 0) return;
auto &val = segt[idx].lazy;
segt[idx].maxDepth += val;
segt[idx].minDepth += val;
segt[idx].leftMax -= val;
segt[idx].rightMax -= val;
if(rangeL != rangeR){
segt[idx * 2].lazy += val;
segt[idx * 2 + 1].lazy += val;
}
val = 0;
return;
}
void merge(Node &head, Node &l, Node &r){
head.maxDepth = max(l.maxDepth, r.maxDepth);
head.minDepth = min(l.minDepth, r.minDepth);
head.leftMax = max(l.leftMax, r.leftMax);
head.leftMax = max(head.leftMax, l.maxDepth - 2 * r.minDepth);
head.rightMax = max(l.rightMax, r.rightMax);
head.rightMax = max(head.rightMax, r.maxDepth - 2 * l.minDepth);
head.diameter = max(l.diameter, r.diameter);
head.diameter = max(head.diameter, l.maxDepth + r.rightMax);
head.diameter = max(head.diameter, r.maxDepth + l.leftMax);
//~ cout << head.maxDepth << " " << head.minDepth << " " << head.leftMax << " " << head.rightMax << " " << head.diameter << endl;
}
void build(int rangeL = 1, int rangeR = dfsTime, int idx = 1){
//~ cout << rangeL << " " << rangeR << " " << idx << endl;
if(rangeL == rangeR){
segt[idx].minDepth = segt[idx].maxDepth = depth[event[rangeL]];
segt[idx].leftMax = segt[idx].rightMax = -depth[event[rangeL]];
return;
}
int mid = (rangeL + rangeR) >> 1;
build(rangeL, mid, idx * 2);
build(mid + 1, rangeR, idx * 2 + 1);
merge(segt[idx], segt[idx * 2], segt[idx * 2 + 1]);
}
void update(int queryL, int queryR, LL val, int rangeL = 1, int rangeR = dfsTime, int idx = 1){
pushDown(rangeL, rangeR, idx);
if(rangeR < queryL) return;
if(queryR < rangeL) return;
if(queryL <= rangeL && rangeR <= queryR){
segt[idx].lazy = val;
pushDown(rangeL, rangeR, idx);
return;
}
int mid = (rangeL + rangeR) >> 1;
update(queryL, queryR, val, rangeL, mid, idx * 2);
update(queryL, queryR, val, mid + 1, rangeR, idx * 2 + 1);
merge(segt[idx], segt[idx * 2], segt[idx * 2 + 1]);
return;
}
}
using namespace DynamicDiameter;
int main() {
cin.tie(0) -> sync_with_stdio(0);
cout.tie(0);
LL n, q, w; cin >> n >> q >> w;
vector <PLL> edges(n - 1);
for (int i = 0; i < n - 1; i++) {
LL c;
cin >> edges[i].fi >> edges[i].se >> c;
edge[edges[i].fi].emplace_back(edges[i].se, c);
edge[edges[i].se].emplace_back(edges[i].fi, c);
}
eulerTour(1);
//~ for(int i = 1;i <= dfsTime;i++) cout << event[i] << " ";
//~ cout << endl;
//~ for(int i = 1;i <= n;i++) cout << i << " " << order[i].fi << " " << order[i].se << endl;
build();
LL ans = 0;
//~ cout << segt[1].diameter << endl;
//~ return 0;
while(q--){
LL d, e; cin >> d >> e;
d = (d + ans) % (n - 1);
e = (e + ans) % w;
auto &edge = edges[d];
if(order[edge.fi].fi > order[edge.se].fi) {
swap(edge.fi, edge.se);
}
// Update the segment tree
//~ cout << e - weights[edge.se] << endl;
//~ cout << segt[1].diameter << endl;
update(order[edge.se].fi, order[edge.se].se, e - weights[edge.se]);
weights[edge.se] = e;
pushDown();
ans = segt[1].diameter;
cout << ans << endl;
}
}
