#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
//using namespace __gnu_pbds;
bool YES(bool f){ if(f) cout << "YES\n" ; else cout << "NO\n" ; return f ; }
void YES(){YES(1);}
void NO(){YES(0);}
void fopn(string name){freopen((name+".in").c_str(),"r",stdin); freopen((name+".out").c_str(),"w",stdout);}
//#define ordered_set tree<int, null_type,less_equal<int>, rb_tree_tag,tree_order_statistics_node_update>
#define ios ios_base::sync_with_stdio(0) ; cin.tie(0) ; cout.tie(0);
#define int long long
#define ld long double
#define pii pair <int , int>
#define all(x) x.begin() , x.end()
#define ff first
#define ss second
#define endl '\n'
const int N = 3e5 + 5 ;
const int inf = 1e16 ;
const int mod = 1e9 + 8 ;
const double eps = 1e-8 ;
template <class T>
bool chmax( T& x , const T& y ){
bool f = 0 ;
if ( x < y ) x = y , f = 1 ;
return f ;
}
template <class T>
bool chmin( T &x , const T &y ){
bool f = 0 ;
if ( x > y ) x = y , f = 1 ;
return f ;
}
//code
int n , q , w , l ;
int a[N] ;
set <pii> g[N] ;
struct edge{
int x , y , z ;
};
int mx = -1 , f ;
vector <edge> v ;
void dfs ( int v , int p , int s ){
//cout << v << ' ' << s << endl ;
if ( chmax ( mx , s ) ) f = v ;
for ( auto to : g[v] ){
if ( to.ff != p ){
//cout << v << ' ' << to.ff << ' ' << to.ss << endl ;
dfs ( to.ff , v , s+to.ss ) ;
}
}
}
void get(){
mx = -1 ;
dfs(1,0,0) ;
mx = -1 ;
dfs(f,0,0) ;
l = mx ;
}
void solve(){
cin >> n >> q >> w ;
for ( int i = 1 ; i < n ; i ++ ){
int x , y , z ; cin >> x >> y >> z ;
g[x].insert({y,z}) ;
g[y].insert({x,z}) ;
v.push_back({x,y,z}) ;
}
if ( max (n,q) <= 5000 ){
for ( int i = 0 ; i < q ; i ++ ){
int a , b ; cin >> a >> b ;
a = (a+l)%(n-1) ; b = (b+l)%w ;
g[v[a].x].erase({v[a].y,v[a].z}) ;
g[v[a].y].erase({v[a].x,v[a].z}) ;
v[a].z = b ;
g[v[a].x].insert({v[a].y,v[a].z}) ;
g[v[a].y].insert({v[a].x,v[a].z}) ;
get() ;
cout << l << endl ;
} return ;
}
multiset <int , greater <int>> vec ;
for ( auto i : g[1] ) vec.insert(i.ss) ;
for ( int i = 0 ; i < q ; i ++ ){
int a , b ; cin >> a >> b ;
a = (a+l)%(n-1) ; b = (b+l)%w ;
vec.erase(vec.find(v[a].z)) ;
v[a].z = b ;
vec.insert(v[a].z) ;
auto it = vec.begin() ;
if ( n == 2 ){
cout << *it << endl ;
l = *it ;
continue ;
} it ++ ; l = *it + *vec.begin() ;
cout << l << endl ;
}
}
signed main(){
ios ;
int t = 1 ;
//cin >> t ;
while ( t -- ) solve() ;
}
