#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;
#define pb push_back
#define all(x) (x).begin(),(x).end()
#define ff first
#define ss second
const int nax = 1e5 + 4;
int n, q;
ll W;
vector<pii> adj[nax];
ll weig[nax];
void solve()
{
cin >> n >> q >> W;
for(int i = 1 ; i < n ;i ++)
{
int a, b;
ll w;
cin >> a >> b >> w;
weig[i] = w;
adj[a].pb({b, i});
adj[b].pb({a, i});
}
ll last = 0ll;
while(q --)
{
ll d, e;
cin >> d >> e;
d = (d + last)%(n - 1);
e = (e + last)%W;
d++;
weig[d] = e;
queue<pll> q;
q.push({1, 0});
pll maxi = {0, 1};\
bool vis[n + 1];
memset(vis, 0, sizeof(vis));
while(!q.empty())
{
int node = q.front().ff;
vis[node] = 1;
ll dis = q.front().ss;
q.pop();
maxi = max(maxi, {dis, node});
for(auto u: adj[node])
{
int nei = u.ff;
int idx = u.ss;
if(vis[nei])
continue;
q.push({nei, dis+ weig[idx]});
}
}
memset(vis, false, sizeof(vis));
q.push({maxi.ss, 0});
//cout << maxi.ss << ' ';
while(!q.empty())
{
int node = q.front().ff;
ll dis = q.front().ss;
q.pop();
vis[node] = 1;
maxi= max(maxi, {dis, node});
for(auto u: adj[node])
{
int nei = u.ff;
int idx = u.ss;
if(vis[nei])
continue;
q.push({nei, dis + weig[idx]});
}
}
cout << maxi.ff << '\n';
last = maxi.ff;
}
}
int32_t main()
{
ios::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
int tt = 1;
while(tt -- )
solve();
}
