#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ii pair<int, int>
#define fi first
#define se second
#define fo(i,a,b) for (int i = (a); i <= (b); ++i)
#define fd(i,a,b) for (int i = (a); i >= (b); --i)
#define all(x) x.begin(), x.end()
#define maxi(a,b) a=max(a,b)
#define mini(a,b) a=min(a,b)
#define ve vector
#define pb push_back
#define er(x) cerr << (#x) << " = " << x << '\n'
#define _ << ' ' <<
#define sus siuuuuu
const int N = 1e6+5, inf = 1e9+10, mod = 1e9+7;
/**
**/
struct node {
ll Hmin, Hmax, Hpre, Hsuf, diam;
node() {
Hmin=Hmax=Hpre=Hsuf=diam=0;
}
node(ll x, ll y, ll z, ll u, ll v) {
Hmin=x, Hmax=y, Hpre=z, Hsuf=u, diam=v;
}
} t[N<<2];
ll la[N<<2];
#define lc (p<<1)
#define rc (lc|1)
void write(int p, ll x) {
t[p].Hmin += x;
t[p].Hmax += x;
t[p].Hpre -= x;
t[p].Hsuf -= x;
la[p] += x;
}
void down(int p) {
if (la[p]) {
write(lc, la[p]);
write(rc, la[p]);
la[p] = 0;
}
}
node mer(node x, node y) {
node z = node();
z.diam = max({x.diam, y.diam, x.Hpre + y.Hmax, x.Hmax + y.Hsuf});
z.Hmin = min(x.Hmin, y.Hmin);
z.Hmax = max(x.Hmax, y.Hmax);
z.Hpre = max({x.Hpre, y.Hpre, x.Hmax - 2LL*y.Hmin});
z.Hsuf = max({x.Hsuf, y.Hsuf, -2LL*x.Hmin + y.Hmax});
return z;
}
void add(int p, int l, int r, int u, int v, ll x) {
if (l>v||r<u) return;
if (u<=l&&r<=v) return write(p, x);
int mid = (l + r) / 2; down(p);
add(lc, l, mid, u, v, x);
add(rc, mid+1, r, u, v, x);
t[p] = mer(t[lc], t[rc]);
}
int n, q, tin[N], tout[N], tour[N], tim;
ll tmp, sum[N];
ve<pair<int, ll>> g[N];
void dfs(int u, int p = -1) {
tim++; tin[u]=tim, tour[tim]=u;
for (auto &x:g[u]) if (x.fi != p) {
sum[x.fi]=sum[u]+x.se;
dfs(x.fi, u);
tour[++tim]=u;
}
tout[u]=tim;
}
void init(int p, int l, int r) {
if (l == r) {
int x=tour[l];
t[p] = node{sum[x],sum[x],-sum[x],-sum[x],0};
return;
}
int mid = (l + r) / 2;
init(lc, l, mid);
init(rc, mid+1, r);
t[p]=mer(t[lc],t[rc]);
}
ve<array<ll,3>> eds;
void solve() {
cin >> n >> q >> tmp;
fo(i,1,n-1) {
ll u, v, c;
cin >> u >> v >> c;
g[u].pb({v,c});
g[v].pb({u,c});
eds.pb({u,v,c});
}
dfs(1);
int m = 2*n-1;
for (auto &v : eds) {
if (tin[v[0]] < tin[v[1]]) swap(v[0],v[1]);
}
init(1,1,m);
ll last = 0;
while (q--) {
ll d, e; cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % tmp;
add(1,1,m,tin[eds[d][0]],tout[eds[d][0]],e-eds[d][2]);
eds[d][2]=e;
last = t[1].diam;
cout << last << '\n';
}
}
signed main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
if (fopen("a.inp","r")) {
freopen("a.inp","r",stdin);
freopen("a.out","w",stdout);
}
solve();
}
