#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ii = pair<ll, ll>;
#define foru(i, l, r) for(int i=(l); i<=(r); ++i)
#define ford(i, l, r) for(int i=(l); i>=(r); --i)
#define fore(x, v) for(auto &x : v)
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
#define fi first
#define se second
#define int long long
#define file "input"
template<class T> bool minimize(T &a, T b) { if (a > b) { a = b; return 1; } return 0; }
template<class T> bool maximize(T &a, T b) { if (a < b) { a = b; return 1; } return 0; }
void setIO() {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
if (fopen(file".inp", "r")) {
freopen(file".inp", "r", stdin);
freopen(file".out", "w", stdout);
}
}
const ll LINF = 1e18;
const int MOD = 998244353;
const int N = 6e5+5;
struct node {
ll mat[3][3];
node() { foru(i, 0, 2) foru(j, i, 2) mat[i][j] = -LINF; }
} sgt[N<<2];
int n, m;
ll W, ew[N], dist[N], lazy[N];
int eu[N], ev[N], st[N], en[N], euler[N], par[N];
vector<int> adj[N];
int cnt;
void dfs_first(int u, int p) {
euler[++cnt] = u;
st[u] = cnt;
fore(i, adj[u]) {
int v = eu[i]^ev[i]^u;
if (v == p) continue;
dist[v] = dist[u] + ew[i];
par[v] = u;
dfs_first(v, u);
euler[++cnt] = u;
}
en[u] = cnt;
}
void apply(int id, ll val) {
lazy[id] += val;
foru(i, 0, 2) foru(j, i, 2) {
int ad = 0;
if (i == 0) ad += 1;
if (i <= 1 && 1 <= j) ad -= 2;
if (j == 2) ad += 1;
sgt[id].mat[i][j] += val * ad;
}
}
void push(int id) {
if (lazy[id] == 0) return;
apply(id*2, lazy[id]);
apply(id*2+1, lazy[id]);
lazy[id] = 0;
}
node comb(node a, node b) {
node c;
foru(i, 0, 2)
foru(j, i, 2) {
c.mat[i][j] = max(a.mat[i][j], b.mat[i][j]);
foru(k, i, j-1) maximize(c.mat[i][j], a.mat[i][k] + b.mat[k+1][j]);
}
return c;
}
void build(int id = 1, int lb = 1, int rb = cnt) {
if (lb ^ rb) {
int k = id << 1, mb = (lb + rb) >> 1;
build(k, lb, mb);
build(k+1, mb+1, rb);
sgt[id] = comb(sgt[k], sgt[k+1]);
}
else {
sgt[id].mat[0][0] = dist[euler[lb]];
sgt[id].mat[1][1] = -2 * dist[euler[lb]];
sgt[id].mat[0][1] = sgt[id].mat[0][0] + sgt[id].mat[1][1];
sgt[id].mat[1][2] = sgt[id].mat[1][1] + sgt[id].mat[2][2];
sgt[id].mat[2][2] = dist[euler[lb]];
sgt[id].mat[0][2] = 0;
}
// cout << lb << " " << rb << " " << sgt[id].mat[1][1] << "\n";
}
void update(int l, int r, ll val, int id = 1, int lb = 1, int rb = cnt) {
if (l <= lb && rb <= r) {
apply(id, val);
return;
}
if (rb < l || lb > r) {
return;
}
int k = id << 1, mb = (lb + rb) >> 1;
push(id);
update(l, r, val, k, lb, mb);
update(l, r, val, k+1, mb+1, rb);
sgt[id] = comb(sgt[k], sgt[k+1]);
// cout << lb << " " << rb << " " << sgt[id].mat[0][1] << "\n";
}
signed main() {
setIO();
cin >> n >> m >> W;
foru(i, 0, n-2) {
cin >> eu[i] >> ev[i] >> ew[i];
adj[eu[i]].push_back(i);
adj[ev[i]].push_back(i);
}
dfs_first(1, 0);
build();
ll lst = 0;
foru(z, 1, m) {
ll x, y;
cin >> x >> y;
x = (x+lst) % (n-1);
y = (y+lst) % W;
if (par[eu[x]] == ev[x]) swap(eu[x], ev[x]);
update(st[ev[x]], en[ev[x]], y - ew[x]);
ew[x] = y;
lst = sgt[1].mat[0][2];
cout << lst << "\n";
}
}
