#include <bits/stdc++.h>
#define mp make_pair
#define ll long long
#define migmig cin.tie(NULL);ios_base::sync_with_stdio(false)
#define max_heap(T) priority_queue<T>
#define min_heap(T) priority_queue<T, vector<T>, greater<T>>
#define pb push_back
#define fi first
#define sec second
#define endl "\n"
#define pii pair <int, ll>
using namespace std;
const ll MOD = 1e9 + 7;
const int INF = 1e9;
const ll INF18 = 6e18;
const int MAXN = 1e5 + 1;
const int LOG = 23;
const int TEST = 25;
bool visited[MAXN];
int st[MAXN], ft[MAXN], timee = 0;
vector <pii> adj[MAXN];
int par[MAXN];
ll a[MAXN], b[MAXN], n, lzy[4 * MAXN];
pair <ll, int> node[4 * MAXN];
int sts[MAXN];
int fuck[MAXN][TEST];
int nf[TEST];
int h[MAXN];
void dfs(int r){
int t = 0;
if (h[r] < TEST) nf[h[r]] = r;
visited[r] = 1, sts[timee] = r, st[r] = timee++;
for (auto i : adj[r]){
if (visited[i.fi] == 0){
t++;
par[i.fi] = r;
h[i.fi] = h[r] + 1;
b[i.fi] = b[r] + i.sec;
dfs(i.fi);
}
}
ft[r] = timee;
for (int i = 0; i <= min(h[r], TEST - 1); i++) fuck[r][i] = nf[i];
}
void build(int l = 0, int r = n, int id = 1){
if (l + 1 == r) node[id] = mp(a[l], l), lzy[id] = 0;
else{
int mid = (l + r) / 2;
build(l, mid, id * 2);
build(mid, r, id * 2 + 1);
if (node[id * 2].fi > node[id * 2 + 1].fi) node[id] = node[id * 2];
else node[id] = node[id * 2 + 1];
lzy[id] = 0;
}
}
pair <ll, int> get(int s, int e, int l = 0, int r = n, int id = 1){
if (s <= l && e >= r) return node[id];
if (s >= r || e <= l) return mp(0, l);
int mid = (l + r) / 2;
lzy[id * 2] += lzy[id];
lzy[id * 2 + 1] += lzy[id];
node[id * 2].fi += lzy[id];
node[id * 2 + 1].fi += lzy[id];
lzy[id] = 0;
auto g1 = get(s, e, l, mid, id * 2), g2 = get(s, e, mid, r, id * 2 + 1);
if (g1.fi > g2.fi) return g1;
else return g2;
}
void upd(int s, int e, ll x, int l = 0, int r = n, int id = 1){
if (s <= l && e >= r){
lzy[id] += x, node[id].fi += x;
return;
}
if (s >= r || e <= l) return;
int mid = (l + r) / 2;
lzy[id * 2] += lzy[id];
lzy[id * 2 + 1] += lzy[id];
node[id * 2].fi += lzy[id];
node[id * 2 + 1].fi += lzy[id];
lzy[id] = 0;
upd(s, e, x, l, mid, id * 2);
upd(s, e, x, mid, r, id * 2 + 1);
if (node[id * 2].fi > node[id * 2 + 1].fi) node[id] = node[id * 2];
else node[id] = node[id * 2 + 1];
}
void solve(){
ll q, w;
cin >> n >> q >> w;
vector <pair <pair <int, int>, ll> > y;
for (int i = 0; i < n - 1; i++){
ll u, v, w;
cin >> u >> v >> w;
adj[u].pb(mp(v, w));
adj[v].pb(mp(u, w));
y.pb(mp(mp(u, v), w));
}
dfs(1);
for (int i = 1; i <= n; i++) a[st[i]] = b[i];
build();
if (n <= 5000 && q <= 5000){
ll last = 0;
for (int i = 0; i < q; i++){
ll d, e;
cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
auto [u, v] = y[d].fi;
ll w1 = y[d].sec;
y[d].sec = e;
if (st[u] > st[v]) swap(u, v);
upd(st[v], ft[v], e - w1);
pair <ll, int> g = get(0, n);
int f = sts[g.sec];
ll maax = g.fi;
while (f != 1){
int u = par[f];
for (auto i : adj[u]){
if (i.fi != f && i.fi != par[u]){
maax = max(maax, g.fi + (get(st[i.fi], ft[i.fi]).fi) - get(st[u], st[u] + 1).fi * 2);
}
}
f = u;
}
cout << maax << endl;
last = maax;
}
}
else{
ll last = 0;
for (int i = 0; i < q; i++){
ll d, e;
cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
auto [u, v] = y[d].fi;
ll w1 = y[d].sec;
y[d].sec = e;
if (st[u] > st[v]) swap(u, v);
upd(st[v], ft[v], e - w1);
pair <ll, int> g = get(0, n);
int f = sts[g.sec];
ll maax = g.fi;
int num = 0;
while (f != 1 && num < TEST){
int u = par[f];
upd(st[f], ft[f], -INF18);
maax = max(maax, get(st[u], ft[u]).fi + g.fi - get(st[u], st[u] + 1).fi * 2);
upd(st[f], ft[f], INF18);
f = u;
num++;
}
f = sts[g.sec];
for (int i = 0; i < min(h[f] - 1, TEST - 1); i++){
int u = fuck[f][i], v = fuck[f][i + 1];
upd(st[v], ft[v], -INF18);
maax = max(maax, get(st[u], ft[u]).fi + g.fi - get(st[u], st[u] + 1).fi * 2);
upd(st[v], ft[v], INF18);
}
cout << maax << endl;
last = maax;
}
}
}
int main(){
migmig;
int tc = 1;
// cin >> tc;
for (int ti = 0; ti < tc; ti++) solve();
}
