#include <bits/stdc++.h>
#define all(x) (x).begin(), (x).end()
#define ff first
#define ss second
#define pb push_back
#define mp make_pair
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll, ll> pll;
typedef pair<ull, ull> pull;
typedef pair<ll, ll> pii;
typedef pair<ld, ld> pld;
struct tree{
vector<ll> seg;
vector<ll> lazy;
ll maxn;
void init(ll n){
maxn = n-1;
seg.resize(4*n);
lazy.resize(4*n);
}
void push(ll v){
seg[2*v] += lazy[v];
seg[2*v+1] += lazy[v];
lazy[2*v] += lazy[v];
lazy[2*v+1] += lazy[v];
lazy[v] = 0;
}
void upd(ll v, ll tl, ll tr, ll l, ll r, ll val){
if(r < tl || tr < l)
return;
if(l <= tl && tr <= r){
seg[v] += val;
lazy[v] += val;
}
else{
push(v);
upd(2*v, tl, (tl+tr)/2, l, r, val);
upd(2*v+1, (tl+tr)/2+1, tr, l, r, val);
seg[v] = max(seg[2*v], seg[2*v+1]);
}
}
ll get(ll v, ll tl, ll tr, ll l, ll r){
if(r < tl || tr < l)
return -1e18;
if(l <= tl && tr <= r){
return seg[v];
}
else{
push(v);
return max(
get(2*v, tl, (tl+tr)/2, l, r),
get(2*v+1, (tl+tr)/2+1, tr, l, r));
}
}
};
struct edge{
ll x, y, z;
};
vector<pll> g[100009];
edge e[100009];
ll sz[100009];
ll block[100009];
void findsz(ll v, ll prt){
sz[v] = 1;
for(auto u : g[v]){
if(block[u.ff] || u.ff == prt) continue;
findsz(u.ff, v);
sz[v] += sz[u.ff];
}
}
ll findcentroid(ll v, ll prt, ll totsz){
for(auto u : g[v]){
if(block[u.ff] || u.ff == prt) continue;
if(sz[u.ff]*2 > totsz)
return findcentroid(u.ff, v, totsz);
}
return v;
}
ll curtime = 0;
ll root;
unordered_map<ll, ll> tin[100009];
unordered_map<ll, ll> tout[100009];
vector<ll> change[100009];
vector<pll> entry[100009];
multiset<ll, greater<ll>> centmax[100009];
ll centans[100009];
tree seg[100009];
multiset<ll, greater<ll>> totmax;
void dfs(ll v, ll prt){
tin[root][v] = curtime++;
ll distoprt;
for(auto u : g[v]){
if(block[u.ff])
continue;
if(u.ff == prt){
change[u.ss].pb(root);
distoprt = e[u.ss].z;
continue;
}
dfs(u.ff, v);
}
tout[root][v] = curtime-1;
seg[root].upd(1, 0, seg[root].maxn, tin[root][v], tout[root][v], distoprt);
}
void decomp(){
findsz(root, 0);
ll totsz = sz[root];
root = findcentroid(root, 0, totsz);
seg[root].init(totsz);
tin[root][root] = -1;
curtime = 0;
for(auto u : g[root]){
if(block[u.ff]) continue;
dfs(u.ff, root);
entry[root].pb({tin[root][u.ff], tout[root][u.ff]});
centmax[root].insert(seg[root].get(1, 0, seg[root].maxn, tin[root][u.ff], tout[root][u.ff]));
}
if(centmax[root].empty()) return;
auto it = centmax[root].begin();
centans[root] = *it;
if(centmax[root].size() >= 2){
++it;
centans[root] += *it;
}
totmax.insert(centans[root]);
block[root] = 1;
ll v = root;
for(auto u : g[v]){
if(block[u.ff]) continue;
root = u.ff;
decomp();
}
}
ll n, q, w;
ll last = 0;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
//freopen("in.txt", "r", stdin);
//freopen("out.txt", "w", stdout);
cin >> n >> q >> w;
for(ll i = 0; i < n-1; ++i){
cin >> e[i].x >> e[i].y >> e[i].z;
g[e[i].x].pb({e[i].y, i});
g[e[i].y].pb({e[i].x, i});
}
root = 1;
decomp();
for(ll i = 0; i < q; ++i){
ll d, val;
cin >> d >> val;
d = (d+last)%(n-1);
val = (val+last)%w;
ll ch = val - e[d].z;
for(auto root : change[d]){
ll v;
if(tin[root][e[d].x] > tin[root][e[d].y])
v = e[d].x;
else
v = e[d].y;
ll in = tin[root][v];
ll out = tout[root][v];
pii cursub = entry[root][upper_bound(all(entry[root]), mp(in, (ll)1e18))-entry[root].begin()-1];
centmax[root].erase(centmax[root].lower_bound(seg[root].get(1, 0, seg[root].maxn, cursub.ff, cursub.ss)));
seg[root].upd(1, 0, seg[root].maxn, in, out, ch);
centmax[root].insert(seg[root].get(1, 0, seg[root].maxn, cursub.ff, cursub.ss));
totmax.erase(totmax.lower_bound(centans[root]));
auto it = centmax[root].begin();
centans[root] = *it;
if(centmax[root].size() >= 2){
++it;
centans[root] += *it;
}
totmax.insert(centans[root]);
}
last = *totmax.begin();
cout << last << '\n';
e[d].z = val;
}
}
