#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld double
#define FOR(i,l,r) for(int i = (l), _r = (r); i <= _r; i++)
#define FORNG(i,r,l) for(int i = (r), _l = (l); i >= _l; i--)
#define REP(i,r) for(int i = 0, _r = (r); i < _r; i++)
#define endl '\n'
#define fi first
#define se second
#define pb push_back
#define size(v) ((int)(v).size())
#define all(v) (v).begin(),(v).end()
#define MASK(x) (1LL << (x))
#define BIT(x, i) (((x) >> (i)) & 1)
const ll MOD = 1e9 + 7, N = 2e5 + 10, LOG = 19;
struct Node{
// a = f[x]
// b = -2f[y]
// c = f[x] - 2f[y]
// d = -2f[y] + f[z]
// e = f[x] - 2f[y] + f[z]
ll a = 0,b = 0,c = 0,d = 0,e = 0;
};
int n,q;
ll W, ew[N];
pair<int,int> edge[N];
vector<int> adj[N];
int t,tin[N],tout[N],tour[N];
void dfs(int u,int p = -1){
tin[u] = ++t;
tour[t] = u;
for(int v : adj[u])if(v != p){
dfs(v, u);
tour[++t] = u;
}
tout[u] = t;
}
Node st[N * 4];
ll lz[N * 4];
void apply(int c,ll val){
st[c].a += val;
st[c].b -= val * 2;
st[c].c -= val;
st[c].d -= val;
lz[c] += val;
}
void push(int c,int l,int r){
if(!lz[c])return;
apply(l, lz[c]);
apply(r, lz[c]);
lz[c] = 0;
}
Node merge(Node l, Node r){
Node res;
res.a = max(l.a, r.a);
res.b = max(l.b, r.b);
res.c = max({l.c, r.c, l.a + r.b});
res.d = max({l.d, r.d, l.b + r.a});
res.e = max({l.e, r.e, max(l.a + r.d, l.c + r.a)});
return res;
}
void update(int u,int v,ll val,int id = 1,int l = 1,int r = t){
if(v < l || r < u)return;
if(u <= l && r <= v){
apply(id, val);
return;
}
int mid = (l + r) >> 1;
push(id, id << 1, id << 1 | 1);
update(u, v, val, id << 1, l, mid);
update(u, v, val, id << 1 | 1, mid + 1, r);
st[id] = merge(st[id << 1], st[id << 1 | 1]);
}
int main(){
//freopen(".INP", "r", stdin);
//freopen(".OUT", "w", stdout);
ios_base::sync_with_stdio(0);cin.tie(0);
cin>>n>>q>>W;
FOR(i,1,n - 1){
int u,v;
cin>>u>>v>>ew[i];
adj[u].pb(v);
adj[v].pb(u);
edge[i] = {u, v};
}
dfs(1);
FOR(i,1,n - 1){
if(tin[edge[i].fi] > tin[edge[i].se])swap(edge[i].fi, edge[i].se);
update(tin[edge[i].se], tout[edge[i].se], ew[i]);
}
ll last = 0;
while(q--){
ll d,e;cin>>d>>e;
d = (d + last) % (n - 1);
e = (e + last) % W;
update(tin[edge[d + 1].se], tout[edge[d + 1].se], e - ew[d + 1]);
ew[d + 1] = e;
cout<<(last = st[1].e)<<endl;
}
}
