#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define ld long double
#define ull unsigned long long
#define ff first
#define ss second
#define pii pair<int,int>
#define pll pair<long long, long long>
#define vi vector<int>
#define vl vector<long long>
#define pb push_back
#define rep(i, b) for(int i = 0; i < (b); ++i)
#define rep2(i,a,b) for(int i = a; i <= (b); ++i)
#define rep3(i,a,b,c) for(int i = a; i <= (b); i+=c)
#define count_bits(x) __builtin_popcountll((x))
#define all(x) (x).begin(),(x).end()
#define siz(x) (int)(x).size()
#define forall(it,x) for(auto& it:(x))
using namespace __gnu_pbds;
using namespace std;
typedef tree<int, null_type, less<int>, rb_tree_tag,tree_order_statistics_node_update> ordered_set;
//mt19937 mt;void random_start(){mt.seed(chrono::time_point_cast<chrono::milliseconds>(chrono::high_resolution_clock::now()).time_since_epoch().count());}
//ll los(ll a, ll b) {return a + (mt() % (b-a+1));}
const int INF = 1e9+50;
const ll INF_L = 1e18+40;
const ll MOD = 1e9+7;
struct segtree
{
pll* max_;
ll* oper;
int tree_siz;
void setup(int n, vi& x)
{
tree_siz = (1<<(__lg(n)+2))-1;
max_ = new pll[tree_siz+1];
oper = new ll[tree_siz+1];
rep2(i,tree_siz/2+1,tree_siz)
{
if(i-(tree_siz/2+1) < siz(x)) max_[i] = {0,x[i-(tree_siz/2+1)]};
else max_[i] = {-1e9,-1};
oper[i] = 0;
}
for(int i = tree_siz/2; i >= 1; i--)
{
max_[i] = max(max_[i*2],max_[i*2+1]);
oper[i] = 0;
}
}
void push(int v)
{
max_[v*2].ff += oper[v];
max_[v*2+1].ff += oper[v];
oper[v*2] += oper[v];
oper[v*2+1] += oper[v];
oper[v] = 0;
}
void add(int akt, int p1, int p2, int s1, int s2, ll x)
{
if(p2 < s1 || p1 > s2) return;
if(p1 >= s1 && p2 <= s2)
{
max_[akt].ff += x;
oper[akt] += x;
return;
}
push(akt);
add(akt*2,p1,(p1+p2)/2,s1,s2,x);
add(akt*2+1,(p1+p2)/2+1,p2,s1,s2,x);
max_[akt] = max(max_[akt*2],max_[akt*2+1]);
}
pll get(int akt, int p1, int p2, int s1, int s2)
{
if(p2 < s1 || p1 > s2) return {-1e9,1};
if(p1 >= s1 && p2 <= s2) return max_[akt];
push(akt);
return max(get(akt*2,p1,(p1+p2)/2,s1,s2),get(akt*2+1,(p1+p2)/2+1,p2,s1,s2));
}
void add_seg(int l, int r, ll x)
{
add(1,0,tree_siz/2,l,r,x);
}
pll get_max(int l, int r)
{
if(l > r) return {-1e9,0};
return get(1,0,tree_siz/2,l,r);
}
};
struct centr_info
{
int v,s_l,s_r,l,r;
};
segtree trees[100001];
vector<pii> graph[100001];
bool odw[100001];
ll cost[100001];
int sub[100001];
vector<centr_info> vert_info[100001];
vector<centr_info> edge_info[100001];
int v1=1,v2=1;
int pre[100001];
int maxpre[100001];
int cur_pre = 0;
vi pre_ls;
void dfs_sub(int v, int pop)
{
sub[v] = 1;
forall(it,graph[v])
{
if(it.ff != pop && !odw[it.ff])
{
dfs_sub(it.ff,v);
sub[v] += sub[it.ff];
}
}
}
void dfs_pre(int v, int pop)
{
pre_ls.pb(v);
pre[v] = cur_pre++;
maxpre[v] = pre[v];
forall(it,graph[v])
{
if(it.ff != pop && !odw[it.ff])
{
dfs_pre(it.ff,v);
maxpre[v] = maxpre[it.ff];
}
}
}
void dfs_add(int v, int pop, int centr, int s_l, int s_r)
{
vert_info[v].pb({centr,s_l,s_r,pre[v],maxpre[v]});
forall(it,graph[v])
{
if(it.ff != pop && !odw[it.ff])
{
edge_info[it.ss].pb({centr,s_l,s_r,pre[it.ff],maxpre[it.ff]});
dfs_add(it.ff,v,centr,s_l,s_r);
}
}
}
void centroid(int v, int n)
{
dfs_sub(v,v);
int pop = v;
while(true)
{
pii best = {0,0};
forall(it,graph[v])
{
if(it.ff != pop && !odw[it.ff])
{
best = max(best,{sub[it.ff],it.ff});
}
}
if(best.ff > n/2)
{
pop = v;
v = best.ss;
}
else break;
}
odw[v] = 1;
dfs_sub(v,v);
cur_pre = 0;
pre_ls = {};
dfs_pre(v,v);
trees[v].setup(n,pre_ls);
vert_info[v].pb({v,-1,-1,0,cur_pre-1});
forall(it,graph[v])
{
if(odw[it.ff]) continue;
dfs_add(it.ff,v,v,pre[it.ff],maxpre[it.ff]);
edge_info[it.ss].pb({v,pre[it.ff],maxpre[it.ff],pre[it.ff],maxpre[it.ff]});
}
forall(it,graph[v])
{
if(!odw[it.ff]) centroid(it.ff,sub[it.ff]);
}
}
ll query(int e, ll c, bool is = 0)
{
forall(it,edge_info[e])
{
trees[it.v].add_seg(it.l,it.r,(!is ? -cost[e] : 0)+c);
}
cost[e] = c;
pll ans1 = {-1,-1};
pll ans2 = {-1,-1};
forall(it,vert_info[v1])
{
pll a1 = trees[it.v].get_max(0,it.s_l-1);
a1.ff += trees[it.v].get_max(it.l,it.l).ff;
pll a2 = trees[it.v].get_max(it.s_r+1,trees[it.v].tree_siz/2);
a2.ff += trees[it.v].get_max(it.l,it.l).ff;
ans1 = max({ans1,a1,a2});
}
forall(it,vert_info[v2])
{
pll a1 = trees[it.v].get_max(0,it.s_l-1);
a1.ff += trees[it.v].get_max(it.l,it.l).ff;
pll a2 = trees[it.v].get_max(it.s_r+1,trees[it.v].tree_siz/2);
a2.ff += trees[it.v].get_max(it.l,it.l).ff;
ans2 = max({ans2,a1,a2});
}
if(ans2.ff > ans1.ff)
{
swap(ans1,ans2);
swap(v1,v2);
}
v2 = ans1.ss;
return ans1.ff;
}
int main()
{
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
//random_start();
int n,q;
ll xd;
cin >> n >> q >> xd;
rep(i,n-1)
{
int a,b;
cin >> a >> b >> cost[i+1];
graph[a].pb({b,i+1});
graph[b].pb({a,i+1});
}
centroid(1,n);
rep2(i,1,n-1) query(i,cost[i],1);
ll last = 0;
rep(qq,q)
{
int e;
ll c;
cin >> e >> c;
e = (e+last)%(n-1);
c = (c+last)%xd;
last = query(e+1,c);
cout << last << "\n";
}
}
