#include <bits/stdc++.h>
#define ll long long
#define left (h<<1),l,((l+r)>>1)
#define right ((h<<1)|1),((l+r)>>1) + 1,r
#define pb push_back
#define pii pair<int,int>
#define s second
#define f first
using namespace std;
const int N = 100005,M=22; // ?
vector <int> v[N],con[N];
multiset <ll> st[N],bigset;
ll value[N],wi[N];
int vis[N],xi[N],yi[N],comp[M],DP[N];
int n,centroid,CH,L;
int tin[M][N],tout[M][N],PAR[M][N],dep[M][N];
ll t[M][4*N],add[M][4*N];
multiset <ll> :: iterator it;
void push(int k,int h){
if (!add[k][h]) return;
add[k][h*2] += add[k][h];
t[k][h*2] += add[k][h];
add[k][h*2+1] += add[k][h];
t[k][h*2+1] += add[k][h];
add[k][h] = 0LL;
}
void upd(int k,int h,int l,int r,int L,int R,ll val){
if (r < L || R < l) return;
if (L <= l && r <= R){
t[k][h] += val;
add[k][h] += val;
return;
}
push(k,h);
upd(k,left,L,R,val);
upd(k,right,L,R,val);
t[k][h] = max(t[k][h*2],t[k][h*2+1]);
}
ll get(int k,int h,int l,int r,int L,int R){
if (r < L || R < l) return 0LL;
if (L <= l && r <= R) return t[k][h];
push(k,h);
return max(get(k,left,L,R),get(k,right,L,R));
}
int dfs(int x,int par,int root,int m){
int s = 1;
for (auto q: v[x]){
int to = x^xi[q]^yi[q];
if (to != par && !vis[to]) s += dfs(to,x,root, m);
}
if (centroid == -1 && (x == root || s*2 >= m)) centroid = x;
return s;
}
void DFS(int x,int par,int id,int cent){
tin[id][x] = ++comp[id];
PAR[id][x] = CH;
for (auto q: v[x]){
int to = x^xi[q]^yi[q];
if (to == par || vis[to]) continue;
con[q].pb(cent);
dep[id][to] = dep[id][x] + 1;
if (dep[id][x] == 1) CH = to;
DFS(to,x,id,cent);
upd(id,1,1,n,tin[id][to],tout[id][to],+wi[q]);
}
tout[id][x] = comp[id];
}
void C(int x,int m,int lvl){
centroid = -1;
dfs(x, x, x, m);
vis[centroid] = 1;
L = max(L,lvl);
DP[centroid] = lvl;
dep[lvl][centroid] = 1;
DFS(centroid,centroid,lvl,centroid);
for (auto q: v[centroid]){
int to = centroid^xi[q]^yi[q];
if (!vis[to]) C(to,m/2,lvl + 1);
}
}
int main(){
// ios_base::sync_with_stdio(0),cin.tie(NULL),cout.tie(NULL);
int q; ll W;
scanf("%d%d%lld",&n,&q,&W);
// cin>>n>>q>>W;
for (int i = 1; i < n; i++){
cin>>xi[i]>>yi[i]>>wi[i];
v[xi[i]].pb(i);
v[yi[i]].pb(i);
}
C(1,n,1);
for (int id = 1; id <= L; id++){
for (int root = 1; root <= n; root++){
if (dep[id][root] != 1) continue;
for (auto q: v[root]){
int to = root^xi[q]^yi[q];
if (dep[id][to] != 2) continue;
st[root].insert(get(id,1,1,n,tin[id][to],tout[id][to]));
}
if (st[root].size() == 1) value[root] = *st[root].begin();
else if (st[root].size() > 1){
it = --st[root].end(); --it;
value[root] = *(--st[root].end()) + *it;
}
bigset.insert(value[root]);
}
}
ll last=0LL;
while (q--){
int d; ll len;
scanf("%d%lld",&d,&len);
// cin>>d>>len;
d = (d + last)%(n-1) + 1;
len = (len + last)%W;
int x = xi[d],y =yi[d]; ll delta = len - wi[d];
wi[d] = len;
for (int root: con[d]){
bigset.erase(bigset.find(value[root]));
int id = DP[root];
if (dep[id][y] > dep[id][x]){
int parent = PAR[id][y];
st[root].erase(st[root].find(get(id,1,1,n,tin[id][parent],tout[id][parent])));
upd(id,1,1,n,tin[id][y],tout[id][y],delta);
st[root].insert(get(id,1,1,n,tin[id][parent],tout[id][parent]));
}
else{
int parent = PAR[id][x];
st[root].erase(st[root].find(get(id,1,1,n,tin[id][parent],tout[id][parent])));
upd(id,1,1,n,tin[id][x],tout[id][x],delta);
st[root].insert(get(id,1,1,n,tin[id][parent],tout[id][parent]));
}
if (st[root].size() == 1) value[root] = *st[root].begin();
else if (st[root].size() > 1){
it = --st[root].end(); --it;
value[root] = *(--st[root].end()) + *it;
}
bigset.insert(value[root]);
}
last = *(--bigset.end());
printf("%lld\n",last);
// cout<<(last = *(--bigset.end()))<<"\n";
}
}
