#include<bits/stdc++.h>
#define pb push_back
#define ii pair<int,int>
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define INF 100000000000000000
#define modulo 1000000007
#define mod 998244353
#define int long long int
using namespace std;
int n;
vector<ii> adj[100005];
vector<ii> edge;
int anc[20][100005];
int depth[100005];
multiset<int> diameter;
multiset<int> data[100005];
map<int, int> ptr;
int getedge(int x, int y){
return lower_bound(all(adj[x]), ii{y, -1}) - adj[x].begin();
}
int getdia(int x){
if(data[x].empty()) return 0;
if(data[x].size() == 1) return *data[x].rbegin();
return *data[x].rbegin() + *++data[x].rbegin();
}
int getmax(int x){
if(data[x].empty()) return 0;
return *data[x].rbegin();
}
void update(int x, int y){
diameter.erase(diameter.find(getdia(x)));
data[x].erase(data[x].lower_bound(ptr[y]));
ptr[y] = getmax(y) + adj[x][getedge(x, y)].second;
data[x].insert(ptr[y]);
diameter.insert(getdia(x));
}
void init(int x, int pre){
for(auto p : adj[x]){
int y = p.first;
if(y == pre) continue;
anc[0][y] = x;
depth[y] = depth[x] + 1;
init(y, x);
data[x].insert(getmax(y) + p.second);
ptr[y] = getmax(y) + p.second;
}
diameter.insert(getdia(x));
}
vector<int> dp(100005, 0);
void naive(int x, int pre){
for(auto p : adj[x]){
int y = p.first;
if(y == pre) continue;
dp[y] = dp[x] + p.second;
naive(y, x);
}
}
int32_t main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int q, W;
cin >> n >> q >> W;
for(int i = 0; i < n - 1; i++){
int x, y, z;
cin >> x >> y >> z;
adj[x].pb({y, z});
adj[y].pb({x, z});
edge.pb({x, y});
}
for(int i = 1; i <= n; i++){
sort(all(adj[i]));
}
init(1, 0);
int last = 0;
while(q--){
ii p;
cin >> p.first >> p.second;
p.first = (p.first + last) % (n - 1);
p.second = (p.second + last) % W;
int x = edge[p.first].first;
int y = edge[p.first].second;
int z = p.second;
adj[x][getedge(x, y)].second = z;
adj[y][getedge(y, x)].second = z;
if(n <= 5000){
int root = 1;
dp = vector<int>(n + 1, 0);
naive(root, -1);
root = max_element(all(dp)) - dp.begin();
dp = vector<int>(n + 1, 0);
naive(root, -1);
last = *max_element(all(dp));
}
else{
if(depth[x] > depth[y]) swap(x, y);
while(x){
update(x, y);
y = x;
x = anc[0][x];
}
last = *diameter.rbegin();
}
cout << last << "\n";
}
}
