#include <bits/stdc++.h>
#define int long long
#define endl '\n'
#define MASK(n) (1LL << n)
#define PhTrNghia "diameter"
using namespace std;
const int maxn = 2e5 + 5;
const int inf = 1e18;
int n, q, w;
vector<pair <int, int>> g[maxn];
pair <int, int> edges[maxn];
int dist[maxn], weight[maxn];
namespace sub1{
void dfs(int u, int p){
for (pair <int, int> cur : g[u]){
int v = cur.first;
int w = cur.second;
if (v == p) continue;
dist[v] = dist[u] + w;
dfs(v, u);
}
}
int get_diameter(){
for (int i = 1; i <= n; i++) dist[i] = 0;
dfs(1, 0);
int tmp1 = 1;
for (int i = 1; i <= n; i++) if (dist[i] > dist[tmp1]) tmp1 = i;
for (int i = 1; i <= n; i++) dist[i] = 0;
dfs(tmp1, 0);
int tmp2 = tmp1;
for (int i = 1; i <= n; i++) if (dist[i] > dist[tmp2]) tmp2 = i;
return dist[tmp2];
}
void solve(){
int last = 0;
while (q--){
int d, e;
cin >> d >> e;
int id = (d + last) % (n - 1) + 1;
int nxt_w = (e + last) % w;
weight[id] = nxt_w;
for (int i = 1; i <= n; i++) g[i].clear();
for (int i = 1; i < n; i++){
int u = edges[i].first;
int v = edges[i].second;
int c = weight[i];
g[u].push_back({v, c});
g[v].push_back({u, c});
}
int ans = get_diameter();
cout << ans << endl;
last = ans;
}
}
}
bool check_sub2 = 1;
namespace sub2{
bool check(){
return check_sub2;
}
multiset <int> st;
void solve(){
for (int i = 1; i < n; i++) st.insert(weight[i]);
int last = 0;
while (q--){
int d, e;
cin >> d >> e;
int id = (d + last) % (n - 1) + 1;
int nxt_w = (e + last) % w;
st.erase(st.find(weight[id]));
weight[id] = nxt_w;
st.insert(weight[id]);
int ans;
if (st.size() == 1) ans = *st.begin();
else {
auto it = st.end();
it--;
int mxf = *it;
it--;
int mxs = *it;
ans = mxf + mxs;
}
cout << ans << endl;
last = ans;
}
}
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
//if (fopen(PhTrNghia".INP", "r")){
//freopen(PhTrNghia".INP", "r", stdin);
//freopen(PhTrNghia".OUT", "w", stdout);
//}
cin >> n >> q >> w;
for (int i = 1; i < n; i++){
int u, v, c;
cin >> u >> v >> c;
if (u != 1) check_sub2 = 0;
edges[i] = {u, v};
weight[i] = c;
}
if (sub2::check()){
sub2::solve();
return 0;
}
sub1::solve();
return 0;
}
/*
4 3 2000
1 2 100
2 3 1000
2 4 1000
2 1030
1 1020
1 890
10 10 10000
1 9 1241
5 6 1630
10 5 1630
2 6 853
10 1 511
5 3 760
8 3 1076
4 10 1483
7 10 40
8 2051
5 6294
5 4168
7 1861
0 5244
6 5156
3 3001
8 5267
5 3102
8 3623
*/
