#include<bits/stdc++.h>
using namespace std;
constexpr int maxn = 4e5+10;
vector<pair<int,int>> g[maxn];
pair<int,int> back[maxn];
int n, q;
int dist[maxn], cost[maxn], w;
void dfs(int u, int p) {
for(auto [v, id] : g[u]) {
if(v != p) {
dist[v] = dist[u] + cost[id];
dfs(v, u);
}
}
}
void brute() {
int last = 0;
while(q--) {
int d, e; scanf("%d %d", &d, &e);
d = (d + last) % (n - 1);
e = (e + last) % w;
cost[d] = e;
dist[1] = 0;
dfs(1, 0);
int x = (int)(max_element(dist+1, dist+n+1) - dist);
dist[x] = 0;
dfs(x, 0);
printf("%d\n", *max_element(dist+1, dist+n+1));
last = *max_element(dist+1, dist+n+1);
}
exit(0);
}
void bst() {
multiset<int, greater<int>> st;
for(int i = 0; i < n-1; i++)
st.insert(cost[i]);
int last = 0;
while(q--) {
int d, e; scanf("%d %d", &d, &e);
d = (int)((d + last) % (n - 1));
e = (int)((e + last) % w);
st.erase(st.find(cost[d]));
cost[d] = e;
st.insert(e);
last = (int)(*st.begin() + (n>2?*next(st.begin()):0));
printf("%d\n", last);
}
exit(0);
}
struct SegmentTree
{
pair<int,int> tree[maxn], G[maxn];
void build(int node) {
sort(g[node].begin(), g[node].end());
reverse(g[node].begin(), g[node].end());
if(g[node].size() == 3 || (g[node].size() == 2 && node>1) || g[node].size() == 1)
g[node].pop_back();
reverse(g[node].begin(), g[node].end());
// printf("%d == ", node);
// for(auto x : g[node])
// printf("%d ", x.first);
// printf("\n");
if(g[node].size()) {
G[node].first = g[node][0].second;
assert(g[node][0].first == 2*node);
build(node<<1);
}
else G[node].first = maxn-10;
if(g[node].size() > 1) {
G[node].second = g[node][1].second;
assert(g[node][1].first == 2*node+1);
build(node<<1|1);
}
else G[node].second = maxn-10;
int vl = tree[2*node].first + cost[G[node].first],
vr = tree[2*node+1].first + cost[G[node].second];
tree[node] = {max(vl, vr),
max({vl+vr, tree[2*node].second, tree[2*node+1].second})};
// printf("%d %d %d\n", node, tree[node].first, tree[node].second);
}
void upd(int node) {
int vl = tree[2*node].first + cost[G[node].first],
vr = tree[2*node+1].first + cost[G[node].second];
tree[node] = {max(vl, vr),
max({vl+vr, tree[2*node].second, tree[2*node+1].second})};
if(node != 1) upd(node>>1);
}
int query() { return tree[1].second; }
} seg;
void solve_seg() {
seg.build(1);
// printf("%d\n", seg.query());
int last = 0;
while(q--) {
int d, e; scanf("%d %d", &d, &e);
d = (int)((d + last) % (n - 1));
e = (int)((e + last) % w);
cost[d] = e;
auto [a, b] = back[d];
if(a > b) swap(a, b);
seg.upd(a);
last = seg.query();
printf("%d\n", last);
}
}
int main() {
scanf("%d %d %d", &n, &q, &w);
// printf("%d %d %d\n", n, q, w);
if(w > 10000) assert(0);
for(int i = 0; i < n-1; i++) {
int a, b; int c; scanf("%d %d %d", &a, &b, &c);
// printf("%d %d %d\n", a, b, c);
g[a].push_back({b, i});
g[b].push_back({a, i});
cost[i] = c;
back[i] = {a, b};
}
if((int)g[1].size() == n-1) bst();
if(n <= 5000) brute();
solve_seg();
}
