using namespace std;
#include <iostream>
#include <algorithm>
#include <queue>
#include <stack>
#include <deque>
#include <map>
#include <set>
#include <utility>
#include <memory.h>
#include <vector>
#include <bitset>
typedef pair<int,int> pii;
typedef long long LL;
#define iter(x) x.begin(),x.end()
#define F first
#define S second
#define pb push_back
#define mkp make_pair
#include <climits>
const int maxn = 1e5+10,mod = 0;
struct EDGE{
int u,v;
LL w;
int con_to(int e){
return u == e ? v : u;
}
}edge[maxn];
vector <int> adj[maxn];
vector <pii> son[maxn];
int father[maxn];
pair<LL,LL> dp[maxn];
LL ans[maxn];
void update(pair <LL,LL> &onto,LL fr){
if (fr > onto.F){
onto.S = onto.F;
onto.F = fr;
}
else if (fr > onto.S){
onto.S = fr;
}
}
void dfs(int x,int fr){
father[x] = fr;
for (auto i:adj[x]) if (edge[i].con_to(x) != fr){
son[x].pb(mkp(edge[i].con_to(x),i));
dfs(edge[i].con_to(x),x);
ans[x] = max(ans[x],ans[edge[i].con_to(x)]);
update(dp[x], dp[edge[i].con_to(x)].F + edge[i].w);
}
ans[x] = max(ans[x],dp[x].F + dp[x].S);
}
void upd(int x){
ans[x] = 0;
dp[x] = {};
for (auto [i,ed]:son[x]){
ans[x] = max(ans[x],ans[i]);
update(dp[x], dp[i].F + edge[ed].w);
}
ans[x] = max(ans[x],dp[x].F + dp[x].S);
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(0);
int n,q,w;
cin >> n >> q >> w;
for (int i=0;i<n-1;++i){
int u,v; LL c;
cin >> u >> v >> c;
edge[i] = {u,v,c};
adj[u].pb(i);
adj[v].pb(i);
}
dfs(1,0);
LL last = 0;
while (q--){
LL d,e;
cin >> d >> e;
d = (d + last) % (n-1);
e = (e + last) % w;
edge[d].w = e;
int u = father[edge[d].u] == edge[d].v ? edge[d].v : edge[d].u;
while (u){
upd(u);
u = father[u];
}
last = ans[1];
cout /*<< d << ' ' << e << ' ' */<< last << '\n';
}
return 0;
}
