#include <bits/stdc++.h>
using namespace std;
#define ll long long
namespace IO { //by cyffff
int len = 0;
char ibuf[(1 << 21) + 1], *iS, *iT, out[(1 << 25) + 1];
#if ONLINE_JUDGE
#define gh() (iS==iT?iT=(iS=ibuf)+fread(ibuf,1,(1<<21)+1,stdin),(iS==iT?EOF:*iS++):*iS++)
#else
#define gh() getchar()
#endif
#define reg register
inline ll read() {
reg char ch = gh();
reg ll x = 0;
reg char t = 0;
while (ch < '0' || ch > '9')
t |= ch == '-', ch = gh();
while (ch >= '0' && ch <= '9')
x = x * 10 + (ch ^ 48), ch = gh();
return t ? -x : x;
}
inline void putc(char ch) {
out[len++] = ch;
}
template<class T>
inline void write(T x) {
if (x < 0)
putc('-'), x = -x;
if (x > 9)
write(x / 10);
out[len++] = x % 10 + 48;
}
inline void flush() {
fwrite(out, 1, len, stdout);
len = 0;
}
inline char getc() {
char ch = gh();
while (ch < 'A' || ch > 'Z')
ch = gh();
return ch;
}
}
using IO::read;
using IO::write;
using IO::flush;
using IO::getc;
using IO::putc;
#define pii pair<int,int>
#define mpr make_pair
#define fir first
#define sec second
using node = array<ll, 3>;
const int N = 2e5 + 10;
int n, q;
ll v;
vector<node>a[N];
struct TopTree {
int cnt, rt, siz[N], son[N], pos[N], ppos[N], fa[N];
struct Data {
int sz;
ll f[2][2];//上界点/下界点
inline ll *operator[](int x) {
return f[x];
}
inline friend Data operator*(Data A, Data B) { //Compess A<-B
Data C;
C.sz = A.sz + B.sz;
C[0][0] = max({A[0][0], B[0][0], A[0][1] + B[1][0]});
C[0][1] = max(B[0][1], A[0][1] + B[1][1]);
C[1][0] = max(A[1][0], A[1][1] + B[1][0]);
C[1][1] = A[1][1] + B[1][1];
return C;
}
inline friend Data operator+(Data A, Data B) { //Rake A<-B
Data C;
C.sz = A.sz + B.sz;
C[0][0] = max({A[0][0], B[0][0], A[1][0] + max(B[1][0], B[1][1])});
C[0][1] = max(A[0][1], A[1][1] + max(B[1][0], B[1][1]));
C[1][0] = max({A[1][0], B[1][0], B[1][1]});
C[1][1] = A[1][1];
return C;
}
};
#define ls tr[rt].lson
#define rs tr[rt].rson
struct node {
int fa, lson, rson, op;
Data v;
} tr[N];
inline void pushup(int rt) {
if (tr[rt].op == 1)
tr[rt].v = tr[ls].v * tr[rs].v;
if (tr[rt].op == 2)
tr[rt].v = tr[ls].v + tr[rs].v;
}
inline Data newdata(ll w) {
Data A;
A.sz = 1;
A[0][0] = A[1][0] = A[1][0] = A[1][1] = w;
return A;
}
inline int newnode(ll w) {
int rt = ++cnt;
tr[rt].v = newdata(w), tr[rt].op = 0;
ls = rs = tr[rt].fa = 0;
return rt;
}
inline int newnode(int lp, int rp, int op) {
int rt = ++cnt;
tr[rt].op = op, ls = lp, rs = rp;
tr[lp].fa = tr[rp].fa = rt;
return pushup(rt), rt;
}
inline void dfs0(int x) {
siz[x] = 1;
for (auto tp : a[x]) {
int t = tp[0], id = tp[2];
ll w = tp[1];
if (t == fa[x])
continue;
ppos[id] = pos[t] = newnode(w);
fa[t] = x, dfs0(t), siz[x] += siz[t];
if (siz[t] > siz[son[x]])
son[x] = t;
}
}
vector<int>pc;
inline int build(int l, int r, int op) {
if (l == r)
return pc[l];
int mid = r - 1, sz = 0;
for (int i = l; i <= r; i++)
sz += tr[pc[i]].v.sz;
for (int i = l, s = 0; i < r; i++) {
s += tr[pc[i]].v.sz;
if (s * 2 >= sz) {
mid = i;
break;
}
}
return newnode(build(l, mid, op), build(mid + 1, r, op), op);
}
inline int dfs(int x) {
vector<int>vc;
if (pos[x])
vc.push_back(pos[x]);
for (int p = x; son[p]; p = son[p]) {
vector<int>vp;
for (auto tp : a[p]) {
int t = tp[0];
if (t == son[p] || t == fa[p])
continue;
vp.push_back(dfs(t));
}
if (!vp.size())
vc.push_back(pos[son[p]]);
else
pc = vp, vc.push_back(newnode(pos[son[p]], build(0, vp.size() - 1, 2), 2));
}
pc = vc;
int rtp = build(0, vc.size() - 1, 1);
return rtp;
}
inline void init() {
dfs0(1), rt = dfs(1);
}
inline void modify(int x, ll w) {
tr[ppos[x]].v = newdata(w);
for (int p = tr[ppos[x]].fa; p; p = tr[p].fa)
pushup(p);
}
inline ll query() {
return max({tr[rt].v[0][0], tr[rt].v[0][1], tr[rt].v[1][0], tr[rt].v[1][1]});
}
} T;
ll las;
int main() {
n = read(), q = read(), v = read();
for (int i = 1; i < n; i++) {
int u = read(), v = read();
ll w = read();
a[u].push_back((node) {
v, w, i
});
a[v].push_back((node) {
u, w, i
});
}
T.init();
while (q--) {
int x = (read() + las) % (n - 1) + 1;
ll w = (read() + las) % v;
T.modify(x, w);
write(las = T.query()), putc('\n');
}
flush();
}
