#include <bits/stdc++.h>
using namespace std;
// #define int long long
const int maxn = 1e5 + 5;
int n, q;
long long w;
namespace subtask12{
struct edge{
int u, v;
long long w;
};
vector<pair<int, long long>> g[5005], ed;
long long dist[5005], ans, last = 0;
void readinput()
{
for(int i = 1; i < n; i++)
{
int u, v;
long long w;
cin >> u >> v >> w;
ed.push_back({u, v});
g[u].push_back({v, w});
g[v].push_back({u, w});
}
}
void dp(int u, int p)
{
dist[u] = 0;
long long maxx = 0;
for(pair<int, long long> res : g[u])
{
int v = res.first;
if(v == p) continue;
dp(v, u);
long long weight = res.second + dist[v];
ans = max(ans, maxx + weight);
maxx = max(maxx, weight);
}
dist[u] = maxx;
}
void solve()
{
readinput();
while(q--)
{
ans = 0;
int d;
long long e;
cin >> d >> e;
d = (last + d) % (n - 1);
e = (e + last) % w;
int u = ed[d].first, v = ed[d].second;
for(pair<int, long long> &res : g[u])
{
if(res.first == v) res.second = e;
}
for(pair<int, long long> &res : g[v])
{
if(res.first == u) res.second = e;
}
dp(1, 1);
cout << ans << '\n';
last = ans;
}
}
}
vector<pair<int,long long>> g[maxn];
struct edge{
int u, v;
long long w;
};
vector<edge> ed;
namespace subtask3
{
int cnt[maxn];
bool check()
{
for(edge x : ed)
{
cnt[x.u]++;
cnt[x.v]++;
}
for(int i = 1; i <= n; i++) if(cnt[i] == n - 1) return 1;
return 0;
}
long long last = 0;
pair<long long, long long> st[4 * maxn];
void build(int v, int l, int r)
{
if(l == r)
{
st[v].first = ed[l - 1].w;
st[v].second = 0;
return;
}
int mid = (l + r) >> 1;
build(v << 1, l, mid);
build(v << 1 | 1, mid + 1, r);
st[v].first = max(st[v << 1].first, st[v << 1 | 1].first);
st[v].second = max({st[v << 1].second, st[v << 1 | 1].second, min(st[v << 1].first, st[v << 1 | 1].first)});
}
void update(int v, int l, int r, int pos, long long val)
{
if(l > pos || r < pos) return;
if(l == r)
{
st[v].first = val;
return;
}
int mid = (l + r) >> 1;
update(v << 1, l, mid, pos, val);
update(v << 1 | 1, mid + 1, r, pos, val);
st[v].first = max(st[v << 1].first, st[v << 1 | 1].first);
st[v].second = max({st[v << 1].second, st[v << 1 | 1].second, min(st[v << 1].first, st[v << 1 | 1].first)});
}
pair<long long, long long> get(int v, int l, int r, const int &b, const int &e)
{
if(l > e || r < b) return {0, 0};
if(l >= b && r <= e) return st[v];
int mid = (l + r) >> 1;
pair<long long, long long> res, maxl = get(v << 1, l, mid + 1, b, e), maxr = get(v << 1 | 1, mid + 1, r, b, e);
res.first = max(maxl.first, maxr.first);
res.second = max({maxl.second, maxr.second, min(maxl.first, maxr.first)});
return res;
}
void solve()
{
build(1, 1, n - 1);
while(q--)
{
int d;
long long e;
cin >> d >> e;
d = (last + d) % (n - 1);
e = (last + e) % w;
update(1, 1, n - 1, d + 1, e);
pair<long long, long long> res = get(1, 1, n - 1, 1, n - 1);
last = res.first + res.second;
cout << last << '\n';
}
}
}
namespace subtask4
{
int num[maxn], tail[maxn], Par[maxn], timeDfs = 0;
pair<int, int> depth[maxn];
long long last = 0, dist[maxn], ans[maxn];
void pre(int u, int p)
{
for(pair<int, long long> v : g[u])
{
if(v.first == p) continue;
Par[v.first] = u;
depth[v.first].first = depth[u].first + 1;
depth[v.first].second = v.first;
pre(v.first, u);
}
for(pair<int, long long> v : g[u])
{
depth[u] = max(depth[u], depth[v.first]);
}
}
void dfs(int u, int p)
{
num[u] = tail[u] = ++timeDfs;
for(pair<int, long long> v : g[u])
{
if(v.first == p) continue;
dfs(v.first, u);
tail[u] = max(tail[u], tail[v.first]);
}
}
void predp(int u, int p)
{
dist[u] = 0;
ans[u] = 0;
long long maxx = 0;
for(pair<int, long long> res : g[u])
{
int v = res.first;
if(v == p) continue;
predp(v, u);
long long weight = res.second + dist[v];
ans[u] = max(ans[u], weight + maxx);
maxx = max(maxx, weight);
ans[u] = max(ans[u], ans[v]);
}
dist[u] = maxx;
}
void recal(int u, int p, int l, int r)
{
ans[u] = 0;
dist[u] = 0;
long long maxx = 0;
for(pair<int, long long> res : g[u])
{
int v = res.first;
if(v == p) continue;
if(num[v] <= l && r <= tail[v]) recal(v, u, l, r);
long long weight = res.second + dist[v];
ans[u] = max(ans[u], weight + maxx);
ans[u] = max(ans[u], ans[v]);
maxx = max(maxx, weight);
}
dist[u] = maxx;
}
int new_root()
{
int maxx = 0, u, maxdepth = 0;
for(pair<int, long long> v : g[1])
{
maxdepth = max(maxdepth, maxx + depth[v.first].first);
if(depth[v.first].first > maxx)
{
// cout << depth[v.first].second << ' ';
maxx = depth[v.first].first;
u = depth[v.first].second;
}
}
// cout << u << '\n';
for(int i = (maxdepth + 1) / 2 - 1; i >= 1; i--) u = Par[u];
return u;
}
void solve()
{
for(int i = 1; i <= n; i++)
{
sort(g[i].begin(), g[i].end());
}
// depth[1] = 1;
pre(1, 1);
// for(int i = 1; i <= n; i++) cout << i << ' ' << depth[i].first << ' ' << depth[i].second << '\n';
int root = new_root();
// cout << root << '\n';
dfs(root, root);
predp(root, root);
while(q--)
{
int d;
long long e;
cin >> d >> e;
d = (last + d) % (n - 1);
e = (e + last) % w;
int u = ed[d].u, v = ed[d].v;
pair<int, long long> res = {v, -1};
auto it = lower_bound(g[u].begin(), g[u].end(), res);
(*it).second = e;
res = {u, -1};
it = lower_bound(g[v].begin(),g[v].end(), res);
(*it).second = e;
// for(pair<int, long long> &res : g[u])
// {
// if(res.first == v) res.second = e;
// }
// for(pair<int, long long> &res : g[v])
// {
// if(res.first == u) res.second = e;
// }
if(tail[u] - num[u] > tail[v] - num[v]) swap(u, v);
recal(root, root, num[u], tail[u]);
cout << ans[root] << '\n';
last = ans[root];
}
}
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n >> q >> w;
for(int i = 1; i < n; i++)
{
int u, v;
long long w;
cin >> u >> v >> w;
ed.push_back({u, v, w});
g[u].push_back({v, w});
g[v].push_back({u, w});
}
if(subtask3::check())
{
subtask3::solve();
return 0;
}
else subtask4::solve();
return 0;
}
