#include <bits/stdc++.h>
#define SZ(x) ((int)x.size())
#define fi first
#define se second
#define pb push_back
#define FOR(i, a, b) for (int i = a, _b = b; i <= _b; ++i)
#define FORD(i, a, b) for (int i = a, _b = b; i >= _b; --i)
#define FORLL(i, a, b) for (ll i = a, _b = b; i <= _b; ++i)
#define FORDLL(i, a, b) for (ll i = a, _b = b; i >= _b; --i)
#define all(x) x.begin(), x.end()
#define uni(x) sort(all(x)), x.erase(unique(all(x)), x.end())
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define dbg(...) debug(#__VA_ARGS__, __VA_ARGS__)
template<typename T>
void __print_one(const char *&s, const T &x)
{
while (*s == ' ') ++s;
const char *p = s;
int bal = 0;
while (*s)
{
if (*s == '(') ++bal;
else if (*s == ')') --bal;
else if (*s == ',' && bal == 0) break;
++s;
}
cerr.write(p, s - p) << " = " << x;
if (*s == ',')
{
++s;
cerr << " , ";
}
}
template<typename... Args>
void debug(const char *s, Args... args)
{
cerr << "[ ";
int dummy[] = { 0 , ( __print_one(s, args) , 0 )... };
(void)dummy;
cerr << " ]\n\n";
}
template<class X>
bool maximize(X &a, X b)
{
if (a < b)
{
a = b;
return true;
}
return false;
}
template<class X>
bool minimize(X &a, X b)
{
if (a > b)
{
a = b;
return true;
}
return false;
}
// --------------------------------------------------------------------------------------------
constexpr int maxn = 1e5 + 3;
int n, q, tin_lca[maxn], tin[maxn], tout[maxn], tdfs_lca, tdfs, tour[maxn], tour_lca[maxn << 1][20], h[maxn], lg[maxn << 1];
ull W, F[maxn]; ll cur_w[maxn];
vector<pair<int, ull>> g[maxn];
pii Eds[maxn];
// --------------------------------------------------------------------------------------------
void readInput()
{
cin >> n >> q >> W;
FOR(i, 2, n)
{
int u, v; ull w; cin >> u >> v >> w;
if (u > v) swap(u, v);
g[u].push_back({v, w});
g[v].push_back({u, w});
Eds[i - 1].fi = u;
Eds[i - 1].se = v;
}
}
#define MIN_H(x, y) (h[x] < h[y] ? x : y)
void dfs_pre(int u, int p)
{
tin[u] = ++tdfs;
tour[tdfs] = u;
tin_lca[u] = ++tdfs_lca;
tour_lca[tdfs_lca][0] = u;
for (const auto &e : g[u])
{
if (e.fi == p) continue;
h[e.fi] = h[u] + 1;
F[e.fi] = F[u] + e.se;
cur_w[e.fi] = e.se;
dfs_pre(e.fi, u);
tour_lca[++tdfs_lca][0] = u;
}
tout[u] = tdfs;
}
int lca(int u, int v)
{
u = tin_lca[u]; v = tin_lca[v];
if (u > v) swap(u, v);
int k = lg[v - u + 1];
return MIN_H(tour_lca[u][k], tour_lca[v - (1 << k) + 1][k]);
}
// Tong tu root --> u
namespace SegDist
{
ull seg[maxn << 2];
void build(int id, int l, int r)
{
if (l == r)
{
seg[id] = F[tour[l]];
return;
}
int mid = l + r >> 1;
build(id << 1, l, mid);
build(id << 1 | 1, mid + 1, r);
}
void push(int id)
{
if (seg[id])
{
seg[id << 1] += seg[id];
seg[id << 1 | 1] += seg[id];
seg[id] = 0;
}
}
void upd(int id, int l, int r, int u, int v, ll w)
{
if (l > v || r < u) return;
if (l >= u && r <= v)
{
seg[id] += w;
return;
}
push(id);
int mid = l + r >> 1;
upd(id << 1, l, mid, u, v, w);
upd(id << 1 | 1, mid + 1, r, u, v, w);
}
ull get(int id, int l, int r, int pos)
{
if (l == r)
{
return seg[id];
}
push(id);
int mid = l + r >> 1;
if (pos <= mid) return get(id << 1, l, mid, pos);
return get(id << 1 | 1, mid + 1, r, pos);
}
}
ull get_dist(int u, int v)
{
return SegDist :: get(1, 1, n, tin[u]) + SegDist :: get(1, 1, n, tin[v]) - 2 * SegDist :: get(1, 1, n, tin[lca(u, v)]);
}
struct Ans
{
int u, v;
Ans()
{
u = v = 0;
}
ull get_cost() const
{
return get_dist(u, v);
}
void updEle(int x)
{
if (x == 0) return;
if (u == 0) u = x;
else if (v == 0) v = x;
else
{
ull dia = get_dist(u, v), diaux = get_dist(u, x), diaxv = get_dist(x, v);
if (diaux > dia && diaux >= diaxv)
{
u = u;
v = x;
}
else if (diaxv > dia && diaxv >= diaux)
{
u = x;
v = v;
}
}
}
};
Ans combine(const Ans &a, const Ans &b)
{
if (b.u == 0 && b.v == 0) return a;
if (a.u == 0 && a.v == 0) return b;
Ans c = a;
c.updEle(b.u);
c.updEle(b.v);
// dbg(a.u, a.v, b.u, b.v, c.u, c.v);
return c;
}
namespace SegDia
{
Ans seg[maxn << 2];
void build(int id, int l, int r)
{
if (l == r)
{
seg[id].u = seg[id].v = tour[l];
return;
}
int mid = l + r >> 1;
build(id << 1, l, mid);
build(id << 1 | 1, mid + 1, r);
seg[id] = combine(seg[id << 1], seg[id << 1 | 1]);
}
void updDia(int id, int l, int r, int u, int v)
{
if (l > v || r < u) return;
if (l >= u && r <= v) return;
int mid = l + r >> 1;
updDia(id << 1, l, mid, u, v); updDia(id << 1 | 1, mid + 1, r, u, v);
seg[id] = combine(seg[id << 1], seg[id << 1 | 1]);
}
}
void solve()
{
// preprocess
dfs_pre(1, -1);
FOR(i, 2, n << 1)
lg[i] = lg[i >> 1] + 1;
FOR(j, 1, 19)
FOR(i, 1, tdfs_lca - (1 << j) + 1)
tour_lca[i][j] = MIN_H(tour_lca[i][j - 1], tour_lca[i + (1 << j - 1)][j - 1]);
SegDist :: build(1, 1, n);
SegDia :: build(1, 1, n);
FOR(i, 1, n - 1)
if (h[Eds[i].fi] < h[Eds[i].se]) swap(Eds[i].fi, Eds[i].se);
// solve
ull LAST = 0;
FOR(iq, 1, q)
{
ll d, e; cin >> d >> e;
d = (d + LAST) % (n - 1);
e = (e + LAST) % W;
++d;
int u = Eds[d].fi;
SegDist :: upd(1, 1, n, tin[u], tout[u], e - cur_w[u]);
SegDia :: updDia(1, 1, n, tin[u], tout[u]);
// dbg(SegDist :: get(1, 1, n, tin[3]));
Ans res = SegDia :: seg[1];
ull ans = res.get_cost();
cout << ans << '\n';
LAST = ans;
cur_w[u] = e;
}
}
signed main()
{
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define TASK "TEST"
if (fopen(TASK".INP", "r"))
{
freopen(TASK".INP", "r", stdin);
freopen(TASK".OUT", "w", stdout);
}
readInput();
solve();
return 0;
}
