//Sylwia Sapkowska
#include <bits/stdc++.h>
#pragma GCC optimize("O3", "unroll-loops")
using namespace std;
void __print(int x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << "'" << x << "'";}
void __print(const char *x) {cerr << '"' << x << '"';}
void __print(const string &x) {cerr << '"' << x << '"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ", "; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? ", " : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifdef LOCAL
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif
#define int long long
typedef pair<int, int> T;
const int oo = 1e18, oo2 = 1e9+7, K = 17;
const int mod = 998244353;
struct Tree{
vector<int>tab, lazy;
int size = 1;
Tree(int n){
while (size < n) size*=2;
tab.assign(2*size, -oo);
lazy.assign(2*size, 0);
}
//dodaj na przedziale max na przedziale
void update(int x, int lx, int rx, int pos, int val){
if (lx == rx) {
tab[x] = val;
return;
}
int m = (lx+rx)/2;
push(x);
if (pos <= m) update(2*x, lx, m, pos, val);
else update(2*x+1, m+1, rx, pos, val);
tab[x] = max(tab[2*x], tab[2*x+1]);
}
void update(int x, int lx, int rx, int l, int r, int val){
if (lx > r || rx < l) return;
if (lx >= l && rx <= r){
tab[x] += val;
lazy[x] += val;
return;
}
int m = (lx+rx)/2;
push(x);
update(2*x, lx, m, l, r, val);
update(2*x+1, m+1, rx, l, r, val);
tab[x] = max(tab[2*x], tab[2*x+1]);
}
void push(int x){
if (!lazy[x]) return;
for (auto k: {2*x, 2*x+1}){
tab[k] += lazy[x];
lazy[k] += lazy[x];
}
lazy[x] = 0;
}
int query(int x, int lx, int rx, int l, int r){
if (lx > r || rx < l) return -oo;
if (lx >= l && rx <= r) return tab[x];
int m = (lx+rx)/2;
push(x);
return max(query(2*x, lx, m, l, r), query(2*x+1, m+1, rx, l, r));
}
};
void solve(){
int n, q, w; cin >> n >> q >> w;
vector<vector<T>>g(n+1);
vector<int>cost(n);
for (int i = 1; i<n; i++){
int a, b; cin >> a >> b >> cost[i];
g[a].emplace_back(b, i);
g[b].emplace_back(a, i);
}
vector<int>sz(n+1);
vector<bool>vis(n+1);
function<int(int, int)>getsz = [&](int v, int pa){
sz[v] = 1;
for (auto [x, i]: g[v]){
if (x == pa || vis[x]) continue;
sz[v] += getsz(x, v);
}
return sz[v];
};
function<int(int, int, int)>get_centroid = [&](int v, int pa, int ms){
for (auto [x, i]: g[v]){
if (x == pa || vis[x]) continue;
if (2*sz[x] > ms) return get_centroid(x, v, ms);
}
return v;
};
int all = 0;
Tree t(n * K);
vector<multiset<int>>vals(n+1);
vector<int>depth(n+1), ord;
vector<vector<array<int, 6>>>where(n+1);
multiset<int>ans;
auto get = [&](int c){
if ((int)vals[c].empty()) return -oo;
if ((int)vals[c].size() == 1) return *vals[c].rbegin();
debug(c, vals[c]);
auto it = --(vals[c].end());
int ans = *it;
it--;
ans += *it;
debug(ans);
return ans;
};
function<void(int)>centroid = [&](int c){
c = get_centroid(c, c, getsz(c, c));
getsz(c, c);
function<void(int, int, int, int)>dfs = [&](int v, int pa, int from, int pos){
for (auto [x, i]: g[v]){
if (x == pa || vis[x]) continue;
from = (v == pa ? x : from);
pos = (v == pa ? all : pos);
// if (v == pa) SZ[{c, from}] = {sz[from], all};
// pos[{c, i}] = {all++, from};
// ord.emplace_back(sz[x]);
where[i].emplace_back(array<int, 6>{c, all++, from, pos, sz[from], sz[x]});
depth[x] = depth[v] + cost[i];
t.update(1, 0, t.size-1, all-1, depth[x]);
dfs(x, v, from, pos);
if (v == pa){
vals[c].insert(t.query(1, 0, t.size-1, pos, pos+sz[x]-1));
}
}
};
depth[c] = 0;
dfs(c, c, -1, -1);
ans.insert(get(c));
debug(c, vals[c]);
vis[c] = 1;
for (auto [x, i]: g[c]){
if (!vis[x]){
centroid(x);
}
}
};
centroid(1);
int last = 0;
debug(ord);
while (q--){
int i, waga; cin >> i >> waga;
i = (i+last)%(n-1) + 1;
waga = (waga+last)%w;
debug(i, cost[i], waga);
int diff = waga - cost[i];
cost[i] = waga;
for (auto [c, pos, from, lfrom, szfr, szx]: where[i]){
debug(c, all, from);
ans.erase(ans.find(get(c)));
vals[c].erase(vals[c].find(t.query(1, 0, t.size-1, lfrom, lfrom+szfr-1)));
t.update(1, 0, t.size-1, pos, pos+szx-1, diff);
vals[c].insert(t.query(1, 0, t.size-1, lfrom, lfrom+szfr-1));
ans.insert(get(c));
}
last = *ans.rbegin();
cout << last << "\n";
// return;
}
}
int32_t main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
solve();
return 0;
}
