#include <bits/stdc++.h>
// #pragma GCC optimize ("Ofast,unroll-loops")
// #pragma GCC target ("avx2")
using namespace std;
typedef long long ll;
typedef pair<ll, int> pp;
#define er(args ...) cerr << __LINE__ << ": ", err(new istringstream(string(#args)), args), cerr << endl
#define per(i,r,l) for(int i = (r); i >= (l); i--)
#define rep(i,l,r) for(int i = (l); i < (r); i++)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
#define pb push_back
#define ss second
#define ff first
void err(istringstream *iss){}template<typename T,typename ...Args> void err(istringstream *iss,const T &_val, const Args&...args){string _name;*iss>>_name;if(_name.back()==',')_name.pop_back();cerr<<_name<<" = "<<_val<<", ",err(iss,args...);}
void IOS(){
cin.tie(0) -> sync_with_stdio(0);
// #ifndef ONLINE_JUDGE
// freopen("in.in", "r", stdin);
// freopen("out.out", "w", stdout);
// #endif
}
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const ll mod = 1e9 + 7, maxn = 1e5 + 5, lg = 22, inf = ll(1e18) + 5;
ll pw(ll a,ll b,ll md=mod){if(!b)return 1;ll k=pw(a,b>>1ll);return k*k%md*(b&1ll?a:1)%md;}
struct Segment{
vector<ll> laz, seg;
int n;
Segment(){}
Segment(vector<ll> a): n(sz(a)){
laz.assign(n<<2, 0), seg.assign(n<<2, 0);
build(1, 0, n, a);
}
void build(int x, int lx, int rx, vector<ll>& a){
if(lx + 1 == rx){
seg[x] = a[lx];
return;
}
int mid = (lx + rx)>>1;
build(x<<1, lx, mid, a), build(x<<1|1, mid, rx, a);
seg[x] = max(seg[x<<1], seg[x<<1|1]);
}
void updNode(int x, ll k){
seg[x] += k, laz[x] += k;
}
void shift(int x){
if(laz[x]){
updNode(x<<1, laz[x]);
updNode(x<<1|1, laz[x]);
laz[x] = 0;
}
}
void upd(int l, int r, ll k, int x, int lx, int rx){
if(l <= lx && r >= rx){
updNode(x, k);
return;
}
shift(x);
int mid = (lx + rx)>>1;
if(l < mid) upd(l, r, k, x<<1, lx, mid);
if(mid < r) upd(l, r, k, x<<1|1, mid, rx);
seg[x] = max(seg[x<<1], seg[x<<1|1]);
}
void upd(int l, int r, ll k){ upd(l, r, k, 1, 0, n); }
ll get(int l, int r, int x, int lx, int rx){
if(l <= lx && r >= rx) return seg[x];
shift(x);
int mid = (lx + rx)>>1;
ll res = 0;
if(l < mid) res = get(l, r, x<<1, lx, mid);
if(mid < r) res = max(res, get(l, r, x<<1|1, mid, rx));
return res;
}
ll get(int l, int r){ return get(l, r, 1, 0, n); }
} seg[maxn];
int cnt[maxn], par[maxn];
vector<pair<int, ll>> adj[maxn];
map<int, int> st[maxn], en[maxn], id[maxn]; int t;
bool ban[maxn];
set<pp> mx[maxn];
#define chk (c-p&&ban[c]^1)
void dfs(int r, int p){
cnt[r] = 1;
for(auto[c, d]: adj[r]) if(chk){
dfs(c, r);
cnt[r] += cnt[c];
}
}
int find_center(int r, int p, int tot){
for(auto[c, d]: adj[r]) if(chk && (cnt[c]<<1) > tot) return find_center(c, r, tot);
return r;
}
vector<ll> tmp;
void dfs2(int r, int p, int cen, ll dist, int ref){
if(p == cen) ref = r;
id[cen][r] = ref;
tmp.pb(dist);
st[cen][r] = t++;
for(auto[c, d]: adj[r]) if(chk) dfs2(c, r, cen, dist + d, ref);
en[cen][r] = t;
}
void reset(int r){
ban[r] = true;
t = 0;
tmp.clear();
}
void dec(int r, int p = -1){
dfs(r, -1);
r = find_center(r, -1, cnt[r]);
par[r] = p;
dfs2(r, -1, r, 0, r);
seg[r] = Segment(tmp);
reset(r);
for(auto[c, d]: adj[r]) if(ban[c]^1) {
dec(c, r), mx[r].insert({seg[r].get(st[r][c], en[r][c]), c});
}
}
set<pp> ans;
ll get_ans(){
return prev(end(ans))->ff;
}
ll get(int r){
if(sz(mx[r]) < 1) return 0;
if(sz(mx[r]) == 1) return begin(mx[r])->ff;
return prev(end(mx[r]))->ff + prev(prev(end(mx[r])))->ff;
}
void upd(int u, int v, ll delta){
auto lis = [&](int u){
vector<int> res;
while(u + 1) res.pb(u), u = par[u];
return res;
};
vector<int> lsu = lis(u), lsv = lis(v);
reverse(all(lsu)), reverse(all(lsv));
vector<int> cand;
rep(i,0,min(sz(lsu), sz(lsv))){
if(lsu[i] - lsv[i]) break;
cand.pb(lsu[i]);
}
for(int r: cand){
if(st[r][u] > st[r][v]) swap(u, v);
int ref = id[r][v];
ans.erase(pp(get(r), r));
mx[r].erase(pp(seg[r].get(st[r][ref], en[r][ref]), ref));
seg[r].upd(st[r][v], en[r][v], delta);
mx[r].insert({seg[r].get(st[r][ref], en[r][ref]), ref});
ans.insert(pp(get(r), r));
}
}
pp edge[maxn];
ll vl[maxn];
int main(){ IOS();
int n, q; cin >> n >> q;
ll W; cin >> W;
rep(i,0,n-1){
int u, v; cin >> u >> v; u--, v--;
ll w; cin >> w;
adj[u].pb({v, w}), adj[v].pb({u, w});
edge[i] = {u, v}, vl[i] = w;
}
dec(0);
rep(i,0,n) ans.insert({get(i), i});
ll lst = 0;
while(q--){
ll d, e; cin >> d >> e;
d = (d + lst)%(n-1), e = (e + lst)%W;
upd(edge[d].ff, edge[d].ss, e - vl[d]);
vl[d] = e;
cout << (lst = get_ans()) << '\n';
}
return 0;
}
