#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 3e5+5;
vector<array<int, 2>> g[N];
int in[N], sub[N];
int C = 1;
int dis[N], idx[N];
int best[N], par[N], deep[N];
void dfs(int u, int p, int IDX){
par[u] = p;
idx[u] = IDX;
in[u] = C++;
sub[u] = 1; int ptr = -1;
for(auto [to, w]: g[u]){
ptr++;
if(to == p) continue;
deep[to] = deep[u]+1;
dis[to] = dis[u] + w;
if(u == 1) dfs(to, u, ptr);
else dfs(to, u, IDX);
sub[u] += sub[to];
}
}
struct Segtree {
vector<int> sg, lz;
void fill(int n) { sg.assign(n*4, 0); lz.assign(n*4, 0); }
void push(int u, int l, int r){
sg[u] += lz[u];
if(l != r){
lz[u*2] += lz[u];
lz[u*2+1] += lz[u];
}
lz[u] = 0;
}
void update(int u, int l, int r, int x, int y, int v){
push(u, l, r);
if(y < l or x > r) return;
if(x <= l and y >= r) {
lz[u] += v;
push(u, l, r);
return;
}
int m = (l+r)/2;
update(u*2, l, m, x, y, v);
update(u*2+1, m+1, r, x, y, v);
sg[u] = max(sg[u*2], sg[u*2+1]);
}
int get(int u, int l, int r, int x, int y){
push(u, l, r);
if(y < l or x > r) return 0;
if(x <= l and y >= r) return sg[u];
int m = (l+r)/2;
auto a1 = get(u*2, l, m, x, y);
auto a2 = get(u*2+1, m+1, r, x, y);
return max(a1, a2);
}
};
multiset<array<int, 2>> V;
void upd(int x, int u){
if(!x) return;
if(best[u]) {
auto it = V.find({best[u], u});
V.erase(it);
V.insert({x, u});
best[u] = x;
return;
}
best[u] = x;
V.insert({x, u});
}
Segtree sg;
int n, q, W;
int BEST(int u){
vector<int> v = {0, 0};
int kp = sg.get(1, 1, n, in[u], in[u]);
for(auto [to, w]: g[u]){
if(to == par[u]) continue;
v.push_back(sg.get(1, 1, n, in[to], in[to]+sub[to]-1) - kp);
}
sort(v.rbegin(), v.rend());
return v[0]+v[1];
}
// for(int i=1; i<=n; i++)
void solve(){
cin >> n >> q >> W;
vector<array<int, 3>> input;
for(int i=1; i<n; i++) {
int x, y, w; cin >> x >> y >> w;
input.push_back({x, y, w});
g[x].push_back({y, w});
g[y].push_back({x, w});
}
dfs(1, 0, 0);
sg.fill(n);
for(int i=1; i<=n; i++) {
sg.update(1, 1, n, in[i], in[i], dis[i]);
}
V = {{0, 0}, {0, 0}};
for(int i=1; i<=n; i++){
upd(BEST(i), i);
}
int last = 0;
while(q--){
int d, aft; cin >> d >> aft;
d = (d+last)%(n-1);
aft = (aft+last)%W;
auto [u, v, bef] = input[d];
if(deep[u] > deep[v]) swap(u, v);
sg.update(1, 1, n, in[v], in[v]+sub[v]-1, aft-bef);
input[d][2] = aft;
// cout << u << ": " << BEST(v) << endl;
while(v){
upd(BEST(v), v);
v = par[v];
}
// cout << aft-bef << endl;
auto it = --V.end();
last = (*it)[0];
cout << last << '\n';
// cout << ans[0] << '\n';
}
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
solve();
}
