#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define ld long double
#define bigint __int128
#define emb emplace_back
#define pb push_back
#define pii pair <int, int>
#define fi first
#define se second
#define all(v) v.begin(), v.end()
#define Task ""
#define MASK(k) (1ull << k)
#define bitcnt(k) __builtin_popcount(k)
#define testBit(n, k) ((n >> k) & 1)
#define flipBit(n, k) (n ^ (1ll << k))
#define offBit(n, k) (n & ~MASK(k))
#define onBit(n, k) (n | (1ll << k))
template <class T> bool minimize(T &a, T b) {if (a > b) {a = b; return true;} return false;}
template <class T> bool maximize(T &a, T b) {if (a < b) {a = b; return true;} return false;}
const int N = 1e5 + 5, lim = 60, mod = 1e9 + 7;
const ll INF = 1e18;
struct SegmentTree { // max dist[u] - 2 * dist[p] + dist[v]
struct Node {
ll A, B, AB, BC, total;
Node () {
A = B = total = -INF;
AB = BC = -INF;
}
Node (ll x) {
A = x; B = -2 * x;
AB = BC = -x;
total = 0;
}
void increase(ll val) {
A += val; B -= 2 * val;
AB -= val; BC -= val;
}
Node operator + (const Node &other) {
Node res;
res.A = max(A, other.A);
res.B = max(B, other.B);
res.AB = max({AB, other.AB, A + other.B});
res.BC = max({BC, other.BC, B + other.A});
res.total = max({total, other.total, A + other.BC, AB + other.A});
return res;
}
};
vector <Node> st;
vector <ll> lazy;
SegmentTree (int n) {
st.assign(n * 4 + 5, Node(0));
lazy.assign(n * 4 + 5, 0);
}
void push_down(int id) {
ll k = lazy[id]; lazy[id] = 0;
st[id << 1].increase(k); lazy[id << 1] += k;
st[id << 1 | 1].increase(k); lazy[id << 1 | 1] += k;
}
void update(int id, int l, int r, int u, int v, ll val) {
if (u > r || v < l) return;
if (u <= l && r <= v) {
st[id].increase(val);
lazy[id] += val;
return;
}
int mid = (l + r) >> 1; push_down(id);
update(id << 1, l, mid, u, v, val);
update(id << 1 | 1, mid + 1, r, u, v, val);
st[id] = st[id << 1] + st[id << 1 | 1];
}
ll get() {
return st[1].total;
}
};
struct Edge {
int u, v; ll w;
Edge () {}
Edge (int a, int b, ll c) {
u = a; v = b; w = c;
}
} edge[N];
int n, q; ll W, dist[N];
vector <int> adj[N];
int childEdge[N];
int tin[N], tout[N], tour[N << 1], dfsTimes = 0;
void dfs(int u, int p = -1) {
tin[u] = tout[u] = ++dfsTimes; tour[dfsTimes] = u;
for (int i: adj[u]) {
int v = edge[i].u ^ edge[i].v ^ u;
if (v != p) {
childEdge[i] = v; dist[v] = dist[u] + edge[i].w;
dfs(v, u);
tout[u] = ++dfsTimes; tour[dfsTimes] = u;
}
}
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
if (fopen(Task".inp", "r")) {
freopen(Task".inp", "r", stdin);
freopen(Task".out", "w", stdout);
}
cin >> n >> q >> W;
for (int i = 0; i < n - 1; i++) {
int u, v; ll w; cin >> u >> v >> w;
edge[i] = Edge(u, v, w);
adj[u].emplace_back(i);
adj[v].emplace_back(i);
}
dfs(1);
SegmentTree ST(dfsTimes);
for (int i = 1; i <= dfsTimes; i++) {
ST.update(1, 1, dfsTimes, i, i, dist[tour[i]]);
}
ll ans = 0;
while (q--) {
ll d, e; cin >> d >> e;
d = (d + ans) % (n - 1);
e = (e + ans) % W;
int v = childEdge[d];
ST.update(1, 1, dfsTimes, tin[v], tout[v], -edge[d].w + e);
edge[d].w = e;
ans = ST.get();
cout << ans << '\n';
}
}
