#include <iostream>
#include <algorithm>
#include <vector>
#include <set>
#include <cstring>
#include <queue>
#include <map>
#include <cmath>
#include <iomanip>
using namespace std;
void __print(int x) { cerr << x; }
void __print(long x) { cerr << x; }
void __print(long long x) { cerr << x; }
void __print(unsigned x) { cerr << x; }
void __print(unsigned long x) { cerr << x; }
void __print(unsigned long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\'' << x << '\''; }
void __print(const char *x) { cerr << '\"' << x << '\"'; }
void __print(const string &x) { cerr << '\"' << x << '\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }
template<typename T, typename V>
void __print(const pair<T, V> &x) {
cerr << '{';
__print(x.first);
cerr << ',';
__print(x.second);
cerr << '}';
}
template<typename T>
void __print(const T &x) {
int f = 0;
cerr << '{';
for (auto &i: x) cerr << (f++ ? "," : ""), __print(i);
cerr << "}";
}
void _print() { cerr << "]\n"; }
template<typename T, typename... V>
void _print(T t, V... v) {
__print(t);
if (sizeof...(v)) cerr << ", ";
_print(v...);
}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif
#define ff first
#define sc second
#define pb push_back
#define ll long long
#define pll pair<ll, ll>
#define pii pair <int, int>
#define ull unsigned long long
#define int long long
// #define int unsigned long long
const ll mod = 1e9 + 7;
const ll weirdMod = 998244353;
const int mxN = 1e5 + 20;
const int lg = 20;
struct node {
int x, y, vl;
} t[4 * mxN];
vector<int> adj[mxN];
int n, q, w, a[mxN], b[mxN], c[mxN], par[mxN][lg], in[mxN], out[mxN], rev[mxN], tim, fen[mxN], lazy[4 * mxN];
bool isanc(int x, int y) {
return (in[x] <= in[y] && out[x] >= out[y]);
}
int lca(int x, int y) {
if (isanc(x, y)) return x;
if (isanc(y, x)) return y;
for (int i = lg - 1; i >= 0; i--)
if (!isanc(par[x][i], y)) x = par[x][i];
return par[x][0];
}
void prop(int v, int tl, int tr) {
if (tl != tr) {
lazy[2 * v] += lazy[v];
lazy[2 * v + 1] += lazy[v];
lazy[v] = 0;
}
}
void update(int v, int tl, int tr, int l, int r, int val) {
if (lazy[v]) prop(v, tl, tr);
if (r < tl || tr < l) return;
if (l <= tl && tr <= r) {
if (tl != tr) {
lazy[2 * v] += val;
lazy[2 * v + 1] += val;
} else lazy[v] += val;
return;
} int tm = (tl + tr) / 2;
update(2 * v, tl, tm, l, min(r, tm), val);
update(2 * v + 1, tm + 1, tr, max(l, tm + 1), r, val);
}
ll get(int v, int tl, int tr, int pos) {
if (lazy[v]) prop(v, tl, tr);
if (tl == tr) return lazy[v];
int tm = (tl + tr) / 2;
if (pos <= tm) return get(2 * v, tl, tm, pos);
return get(2 * v + 1, tm + 1, tr, pos);
}
int query(int x, int y) {
return get(1, 1, n, in[x]) + get(1, 1, n, in[y]) - 2 * get(1, 1, n, in[lca(x, y)]);
}
void dfs(int v, int p) {
in[v] = ++tim;
par[v][0] = p;
rev[in[v]] = v;
for (int i = 1; i < lg; i++)
par[v][i] = par[par[v][i - 1]][i - 1];
for (int u : adj[v])
if (u != p) dfs(u, v);
out[v] = tim;
}
void merge(int v, int x, int y) {
int mx, a, b;
if (t[x].vl > t[y].vl) {
mx = t[x].vl; a = t[x].x; b = t[x].y;
} else {
mx = t[y].vl; a = t[y].x; b = t[y].y;
} for (int i = 0; i < 2; i++) {
for (int j = 0; j < 2; j++) {
int dx = t[x].x, dy = t[y].x;
if (i) dx = t[x].y;
if (j) dy = t[y].y;
int cr = query(dx, dy);
if (cr > mx) {
mx = cr; a = dx; b = dy;
}
}
} t[v].vl = mx; t[v].x = a; t[v].y = b;
}
void build(int v, int tl, int tr) {
if (tl == tr) {
t[v].vl = 0;
t[v].x = rev[tl];
t[v].y = rev[tl];
return;
} int tm = (tl + tr) / 2;
build(2 * v, tl, tm);
build(2 * v + 1, tm + 1, tr);
merge(v, 2 * v, 2 * v + 1);
}
void update(int v, int tl, int tr, int l, int r) {
if (r < tl || tr < l) return;
if (l <= tl && tr <= r) return;
int tm = (tl + tr) / 2;
update(2 * v, tl, tm, l, min(r, tm));
update(2 * v + 1, tm + 1, tr, max(l, tm + 1), r);
merge(v, 2 * v, 2 * v + 1);
}
void solve() {
cin >> n >> q >> w;
for (int i = 1; i < n; i++) {
cin >> a[i] >> b[i] >> c[i];
adj[a[i]].pb(b[i]); adj[b[i]].pb(a[i]);
} dfs(1, 1);
for (int i = 1; i < n; i++) {
if (in[a[i]] < in[b[i]]) swap(a[i], b[i]);
update(1, 1, n, in[a[i]], out[a[i]], c[i]);
} build(1, 1, n);
int last = 0, d, e;
while (q--) {
cin >> d >> e;
d = (d + last) % (n - 1) + 1;
e = (e + last) % w;
update(1, 1, n, in[a[d]], out[a[d]], -c[d]);
c[d] = e;
update(1, 1, n, in[a[d]], out[a[d]], c[d]);
update(1, 1, n, in[a[d]], out[a[d]]);
cout << t[1].vl << '\n'; last = t[1].vl;
}
}
int32_t main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
int t = 1;
// cin >> t;
while (t--) {
solve();
cout << '\n';
}
return 0;
}
