// Knapsack DP is harder than FFT.
#include<bits/stdc++.h>
using namespace std;
typedef long long ll; typedef pair<int,int> pii; typedef pair<ll,ll> pll;
#define ff first
#define ss second
#define pb emplace_back
#define AI(x) begin(x),end(x)
template<class I>bool chmax(I&a,I b){return a<b?(a=b,true):false;}
template<class I>bool chmin(I&a,I b){return b<a?(a=b,true):false;}
#ifdef OWO
#define debug(args...) SDF(#args, args)
#define OIU(args...) ostream& operator<<(ostream&O,args)
#define LKJ(S,B,E,F) template<class...T>OIU(S<T...>s){O<<B;int c=0;for(auto i:s)O<<(c++?", ":"")<<F;return O<<E;}
LKJ(vector,'[',']',i)LKJ(deque,'[',']',i)LKJ(set,'{','}',i)LKJ(multiset,'{','}',i)LKJ(unordered_set,'{','}',i)LKJ(map,'{','}',i.ff<<':'<<i.ss)LKJ(unordered_map,'{','}',i.ff<<':'<<i.ss)
template<class...T>void SDF(const char* s,T...a){int c=sizeof...(T);if(!c){cerr<<"\033[1;32mvoid\033[0m\n";return;}(cerr<<"\033[1;32m("<<s<<") = (",...,(cerr<<a<<(--c?", ":")\033[0m\n")));}
template<class T,size_t N>OIU(array<T,N>a){return O<<vector<T>(AI(a));}template<class...T>OIU(pair<T...>p){return O<<'('<<p.ff<<','<<p.ss<<')';}template<class...T>OIU(tuple<T...>t){return O<<'(',apply([&O](T...s){int c=0;(...,(O<<(c++?", ":"")<<s));},t),O<<')';}
#else
#pragma GCC optimize("Ofast")
#define debug(...) ((void)0)
#endif
typedef tuple<int, int, ll> triple;
const int kN = 100001;
int n, q; ll w;
pii edg[kN]; ll wei[kN];
vector<pll> adj[kN];
int par[kN];
ll dep[kN], dp[kN];
multiset<ll> s;
void dfs(int u, int p){
par[u] = p;
for(auto [v, w]: adj[u]){
if(v == p) continue;
dfs(v, u);
ll d = dep[v] + wei[w];
chmax(dp[u], dep[u] + d);
chmax(dep[u], d);
}
s.insert(dp[u]);
}
void init(){
dfs(1, -1);
}
void rm(ll v){
auto it = s.find(v);
s.erase(it);
}
ll upd(ll d, ll e){
debug(d, e);
auto &[a, b] = edg[d];
wei[d] = e;
if(par[a] == b) swap(a, b);
int p = a, u = b;
while(p != -1){
debug(u, p);
rm(dp[p]);
dp[p] = 0;
dep[p] = 0;
for(auto [v, w]: adj[p]){
if(v == par[p] or v == b) continue;
ll dd = dep[v] + wei[w];
debug(v, dd);
chmax(dp[p], dep[p] + dd);
chmax(dep[p], dd);
}
if(p == a){
chmax(dp[p], dep[p] + dep[b] + e);
chmax(dep[p], dep[b] + e);
}
s.insert(dp[p]);
debug(dep[p], dp[p]);
u = p; p = par[p];
}
return *s.rbegin();
}
signed main(){
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin >> n >> q >> w;
for(int i = 0; i < n-1; ++i){
int u, v; ll c; cin >> u >> v >> c;
edg[i] = pii(u, v);
wei[i] = c;
adj[u].pb(v, i);
adj[v].pb(u, i);
}
init();
ll last = 0;
for(int i = 0; i < q; ++i){
ll d, e; cin >> d >> e;
d = (d + last) % (n-1);
e = (e + last) % w;
cout << (last = upd(d, e)) << '\n';
}
return 0;
}
