// Only GOD
// Believe in yourself!
// -o Sango zadam be shishe
// -o Comeback bezan hamishe!
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
#define pb push_back
#define F first
#define S second
#define bit(x, y) (x >> y)&1
#define all(x) x.begin(), x.end()
#define sz(x) (int)x.size()
#define kill(x) return cout << x << '\n', void()
#define KILL(x) return cout << x << '\n', 0
#define int ll
#define mid ((l+r)>>1)
#define lid (id << 1)
#define rid (lid | 1)
const int N = 3e5+10;
const int INF = 1e9+10;
int n, q, W;
vector<pii> G[N];
int edge[N], dp[N], maxout[N], lst, h[N];
//pii EDGE[N];
//map<pii, int> E;
//// chinese seg:)
//void upd(int id){
// int mx1 = maxout[lid] + E[{id, lid}], mx2 = maxout[rid] + E[{id, rid}];
// maxout[id] = max(mx1, mx2);
// dp[id] = mx1 + mx2;
// lst = max({lst, dp[id], dp[rid], dp[lid]});
// id >>= 1;
// for(; id > 0; id >>= 1){
// int mx1 = maxout[lid] + E[{id, lid}], mx2 = maxout[rid] + E[{id, rid}];
// maxout[id] = max(mx1, mx2);
// dp[id] = mx1 + mx2;
// lst = max({lst, dp[id], dp[rid], dp[lid]});
// }
//}
void DFS(int v, int p = -1){
int mx1 = -1, mx2 = -1;
for(auto x : G[v]){
if(x.F == p)
continue;
h[x.F] = h[v] + 1;
DFS(x.F, v);
if(edge[x.S] + maxout[x.F] >= mx1){
swap(mx1, mx2);
mx1 = edge[x.S] + maxout[x.F];
}
else if(edge[x.S] + maxout[x.F] > mx2){
mx2 = edge[x.S] + maxout[x.F];
}
}
maxout[v] = (mx1==-1 ? 0 : mx1);
if(mx2 != -1){
dp[v] = mx1 + mx2;
}
}
int32_t main(){
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin >> n >> q >> W;
bool f = 0;
for(int i = 0; i < n-1; i++){
int v, u, w;
cin >> v >> u >> w;
G[v].pb({u, i});
G[u].pb({v, i});
if(v != 1 && u != 1)
f = 1;
edge[i] = w;
// EDGE[i]={v, u};
// E[{v, u}]=w;
// E[{u, v}]=w;
}
lst = 0;
if(n <= 5001 && q <= 5001){
while(q--){
int d, e;
cin >> d >> e;
edge[(d+lst)%(n-1)] = (e+lst)%W;
DFS(1);
lst = 0;
for(int i = 1; i <= n; i++)
lst = max({lst, dp[i], maxout[i]});
cout << lst << '\n';
}
}
else{
set<pii> s;
for(int i = 0; i < n-1; i++){
s.insert({edge[i], i});
}
while(q--){
int d, e;
cin >> d >> e;
int XX = (d+lst)%(n-1), YY = (e+lst)%W;
s.erase({edge[XX], XX});
edge[XX] = YY;
s.insert({edge[XX], XX});
auto itr = s.rbegin();
lst = (*itr).F;
itr--;
lst += (*itr).F;
cout << lst << '\n';
}
}
// else{
// DFS(1);
// while(q--){
// int d, e;
// cin >> d >> e;
// edge[(d+lst)%(n-1)] = (e+lst)%W;
// int v = EDGE[(d+lst)%(n-1)].F, u = EDGE[(d+lst)%(n-1)].S;
// E[{v, u}] = (e+lst)%W;
// E[{u, v}] = E[{v, u}];
// if(u < v)
// swap(v, u);
// lst = 0;
// upd(v);
// cout << lst << '\n';
// }
// }
}
