#include <iostream>
#include <vector>
#include <queue>
using namespace std;
using ll = long long;
using pll = pair<ll, ll>;
using vll = vector<ll>;
using vi = vector<int>;
const int mx = 15'000;
const ll INF = 2'000'000'000'000'000'000LL;
int a[1+mx], b[1+mx];
ll l[1+mx];
vi edge[1+mx];
int n, q;
ll w;
vll getdistances(int src)
{
vll res(1+n, INF);
res[src] = 0;
queue<int> tbv;
tbv.push(src);
while(!tbv.empty())
{
int u = tbv.front();
tbv.pop();
for(int e : edge[u])
{
int v = a[e] + b[e] - u;
ll w = l[e];
if(res[v] <= res[u] + w) continue;
res[v] = res[u] + w;
tbv.push(v);
}
}
return res;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> q;
cin >> w;
for(int e = 1; e <= n-1; e++)
{
cin >> a[e] >> b[e] >> l[e];
edge[a[e]].push_back(e);
edge[b[e]].push_back(e);
}
ll last = 0;
for(int j = 1; j <= q; j++)
{
ll d, e;
cin >> d >> e;
d = ((d + last) % (n-1)) + 1;
e = (e + last) % w;
l[d] = e;
vll zd = getdistances(1);
int mx = 1;
for(int i = 2; i <= n; i++)
if(zd[i] > zd[mx])
mx = i;
vll zd2 = getdistances(mx);
last = 0;
for(int i = 1; i <= n; i++)
last = max(last, zd2[i]);
cout << last << '\n';
}
}
