// source problem :
#include <bits/stdc++.h>
using namespace std;
#define all(x) x.begin(), x.end()
#define int long long
#define MASK(i) (1LL << (i))
void ckmax(int& f, int s)
{
f = (f > s ? f : s);
}
void ckmin(int& f, int s)
{
f = (f < s ? f : s);
}
int lz[1 << 19] = {};
const int inf = 1e18;
struct info
{
int a[3][3];
info()
{
for (int i = 0; i < 3; i++) for (int j = i; j < 3; j++) a[i][j] = -inf;
}
info(int x)
{
// i <= j <= k
// val[i] - 2 * val[j] + val[k]
a[0][0] = x;
a[0][1] = -x;
a[0][2] = 0;
a[1][1] = -2 * x;
a[1][2] = -x;
a[2][2] = x;
}
void change(int x)
{
a[0][0] += x;
a[0][1] -= x;
a[1][1] -= 2 * x;
a[1][2] -= x;
a[2][2] += x;
}
};
info operator+(info a, info b)
{
if (a.a[0][0] < 0) return b;
if (b.a[0][0] < 0) return a;
info res;
for (int i = 0; i < 3; i++)
{
for (int j = i; j < 3; j++)
{
res.a[i][j] = max(a.a[i][j], b.a[i][j]);
for (int k = i + 1; k <= j; k++)
{
ckmax(res.a[i][j], a.a[i][k - 1] + b.a[k][j]);
}
}
}
return res;
}
info st[1 << 19];
void down(int id)
{
if (!lz[id]) return;
for (int i : {id << 1, id << 1 | 1})
{
lz[i] += lz[id];
st[i].change(lz[id]);
}
lz[id] = 0;
}
void init(int u, int v, int x, int id = 1, int l = 1, int r = 1 << 18)
{
if (r < u || l > v) return;
if (l >= u && r <= v)
{
st[id] = info(x);
return;
}
int mid = (l + r) >> 1;
down(id);
init(u, v, x, id << 1, l, mid);
init(u, v, x, id << 1 | 1, mid + 1, r);
st[id] = st[id << 1] + st[id << 1 | 1];
}
void update(int u, int v, int x, int id = 1, int l = 1, int r = 1 << 18)
{
if (r < u || l > v) return;
if (l >= u && r <= v)
{
lz[id] += x;
st[id].change(x);
return;
}
int mid = (l + r) >> 1;
down(id);
update(u, v, x, id << 1, l, mid);
update(u, v, x, id << 1 | 1, mid + 1, r);
st[id] = st[id << 1] + st[id << 1 | 1];
}
int32_t main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
int n, q, _w;
cin >> n >> q >> _w;
vector<int> et = {0}, w(n), h(n), val(n);
vector<vector<pair<int, int>>> adj(n);
vector<tuple<int, int, int>> e;
for (int i = 0; i < n - 1; i++)
{
int u, v, ww;
cin >> u >> v >> ww;
u--, v--;
adj[u].emplace_back(v, ww);
adj[v].emplace_back(u, ww);
e.emplace_back(u, v, ww);
}
function<void(int, int)> dfs = [&](int u, int p)
{
et.push_back(u);
for (auto [v, ww] : adj[u])
{
if (v == p) continue;
h[v] = h[u] + 1;
val[v] = ww;
w[v] = w[u] + ww;
dfs(v, u);
et.push_back(u);
}
};
dfs(0, 0);
for (int i = 1; i < et.size(); i++)
{
init(i, i, w[et[i]]);
}
vector<int> in(n, -1), out(n);
for (int i = 1; i < et.size(); i++)
{
out[et[i]] = i;
if (in[et[i]] == -1) in[et[i]] = i;
}
for (auto &[u, v, ww] : e)
{
if (h[u] < h[v]) swap(u, v);
}
int last = 0;
while (q--)
{
int i, x;
cin >> i >> x;
i = (i + last) % (n - 1);
x = (x + last) % _w;
int u = get<0>(e[i]);
int dif = x - val[u];
update(in[u], out[u], dif);
val[u] = x;
//cout << dif << '\n';
last = st[1].a[0][2];
cout << last << '\n';
}
return 0;
}
