#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx2,tune=native")
#define int long long int
typedef long long ll;
const int MAX = 2e5 + 15;
const int INF = 0x3f3f3f3f;
int n, q, wlim, h[MAX], v[MAX], tin[MAX], tout[MAX], timer;
tuple<int, int, int> edges[MAX];
vector<pair<int, int>> adj[MAX];
struct Node{
ll Mi, Mj, Mk, Mij, Mjk, Mijk, lzSum;
Node(ll a = 0, ll b = 0, ll c = 0, ll d = 0, ll e = 0, ll f = 0, ll g = 0) :
Mi(a), Mj(b), Mk(c), Mij(d), Mjk(e), Mijk(f), lzSum(g) { }
Node operator + (Node other){
Node ret;
ret.Mi = max(Mi, other.Mi);
ret.Mj = min(Mj, other.Mj);
ret.Mk = max(Mk, other.Mk);
ret.Mij = max({ Mij, other.Mij, Mi - 2 * other.Mj });
ret.Mjk = max({ Mjk, other.Mjk, other.Mk - 2 * Mj });
ret.Mijk = max({ Mijk, other.Mijk, Mij + other.Mk, Mi + other.Mjk });
return ret;
}
} seg[4 * MAX];
void refresh(int p, int l, int r){
if(seg[p].lzSum == 0) return;
int add = seg[p].lzSum; seg[p].lzSum = 0;
seg[p].Mi += add;
seg[p].Mj += add;
seg[p].Mk += add;
seg[p].Mij -= add;
seg[p].Mjk -= add;
if(l == r) return;
int e = 2 * p, d = e + 1;
seg[e].lzSum += add;
seg[d].lzSum += add;
}
void build(int p, int l, int r){
if(l == r){
seg[p] = Node(v[l], v[l], v[l], -v[l], -v[l], 0, 0);
return;
}
int m = (l + r) >> 1, e = 2 * p, d = e + 1;
build(e, l, m); build(d, m + 1, r);
seg[p] = seg[e] + seg[d];
}
void update(int a, int b, int x, int p, int l, int r){
refresh(p, l, r);
if(a > r || b < l) return;
if(a <= l && r <= b){
seg[p].lzSum += x;
refresh(p, l, r);
return;
}
int m = (l + r) >> 1, e = 2 * p, d = e + 1;
update(a, b, x, e, l, m); update(a, b, x, d, m + 1, r);
seg[p] = seg[e] + seg[d];
}
void dfs(int u, int p){
tin[u] = ++timer;
v[ tin[u] ] = h[u];
for(auto [v, w] : adj[u]){
if(v == p) continue;
h[v] = h[u] + w;
dfs(v, u);
}
tout[u] = ++timer;
v[ tout[u] ] = h[p];
}
int32_t main(void){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> q >> wlim;
for(int i = 1; i < n; i++){
auto &[u, v, w] = edges[i];
cin >> u >> v >> w;
adj[u].emplace_back(v, w);
adj[v].emplace_back(u, w);
}
dfs(1, 1);
build(1, 1, 2 * n);
int last = 0;
auto getI = [&](int i){ return (i + last) % (n - 1); };
auto getW = [&](int w){ return (w + last) % (wlim); };
while(q--){
int i, newW; cin >> i >> newW;
i = getI(i), newW = getW(newW);
auto &[u, v, w] = edges[i + 1];
if(tin[u] < tin[v]) swap(u, v);
update(tin[u], tout[u] - 1, newW - w, 1, 1, 2 * n);
w = newW;
last = seg[1].Mijk;
cout << last << '\n';
}
}
