#include "bits/stdc++.h"
using namespace std;
template<typename A> ostream& operator<<(ostream& os, vector<A> x) {os << "{"; string sep; for (A y : x) os << sep << y, sep = ", "; return os << "}";}
#define all(a) (a).begin(), (a).end()
#define ll long long
#define lid id << 1
#define rid id << 1 | 1
#define mid ((r + l) >> 1)
const ll MAX_N = 1e5 + 5;
const ll MOD = 1e9 + 7;
const ll INF = 1e18;
const ll LOG = 30;
ll ps[MAX_N];
vector<pair<ll, ll>> adj[MAX_N];
vector<ll> al;
ll st[MAX_N];
ll fi[MAX_N];
ll w1[MAX_N];
ll u1[MAX_N], v1[MAX_N];
ll h[MAX_N];
void dfs(ll u, ll p)
{
st[u] = al.size();
al.push_back(u);
for (auto v : adj[u]) if (v.first != p) h[v.first] = h[u] + v.second, ps[v.first] = ps[u] + v.second, dfs(v.first, u), al.push_back(u);
fi[u] = al.size();
}
struct node
{
ll ans[3][3];
node(){};
};
node merge(node x, node y)
{
node re;
for (ll i = 0; i < 3; i++) for (ll j = i; j < 3; j++)
{
re.ans[i][j] = max(x.ans[i][j], y.ans[i][j]);
for (ll p = i; p < j; p++) re.ans[i][j] = max(re.ans[i][j], x.ans[i][p] + y.ans[p + 1][j]);
}
return re;
}
node seg[MAX_N << 3];
ll ops[MAX_N << 2];
void build(ll l, ll r, ll id)
{
if (l == r - 1)
{
for (ll i = 0; i < 3; i++)
{
ll sum = 0;
for (ll j = i; j < 3; j++)
{
if (j == 1) sum -= 2;
else sum++;
seg[id].ans[i][j] = 1ll * sum * ps[al[l]];
}
}
return;
}
build(l, mid, lid);
build(mid, r, rid);
seg[id] = merge(seg[lid], seg[rid]);
}
void move(ll l, ll r, ll id)
{
if (l == r - 1) return;
for (ll i = 0; i < 3; i++)
{
ll sum = 0;
for (ll j = i; j < 3; j++)
{
if (j == 1) sum -= 2;
else sum++;
seg[lid].ans[i][j] += 1ll * sum * ops[id];
seg[rid].ans[i][j] += 1ll * sum * ops[id];
}
}
ops[lid] += ops[id];
ops[rid] += ops[id];
ops[id] = 0;
}
void upd(ll s, ll t, ll x, ll l, ll r, ll id)
{
move(l, r, id);
if (s <= l && t >= r)
{
ops[id] += x;
for (ll i = 0; i < 3; i++)
{
ll sum = 0;
for (ll j = i; j < 3; j++)
{
if (j == 1) sum -= 2;
else sum++;
seg[id].ans[i][j] += 1ll * sum * x;
}
}
return;
}
if (s < mid) upd(s, t, x, l, mid, lid);
if (t > mid) upd(s, t, x, mid, r, rid);
seg[id] = merge(seg[lid], seg[rid]);
}
void solve()
{
ll n, q;
cin >> n >> q;
ll w;
cin >> w;
ll last = 0;
for (ll i = 0; i < n - 1; i++)
{
cin >> u1[i] >> v1[i] >> w1[i];
adj[u1[i]].push_back({v1[i], w1[i]});
adj[v1[i]].push_back({u1[i], w1[i]});
}
dfs(1, 0);
build(0, al.size(), 1);
while (q--)
{
ll d; ll e;
cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
if (h[u1[d]] > h[v1[d]]) swap(u1[d], v1[d]);
upd(st[v1[d]], fi[v1[d]], e - w1[d], 0, al.size(), 1);
w1[d] = e;
cout << (last = seg[1].ans[0][2]) << endl;
}
}
ll main()
{
cin.tie(NULL); cout.tie(NULL); ios_base::sync_with_stdio(false);
ll tc = 1;
// cin >> tc;
while (tc--) solve();
}
