#include <bits/stdc++.h>
#define pb emplace_back
#define ll long long
#define fi first
#define se second
#define mp make_pair
//#define int int64_t
using namespace std;
const int N = (int)1e5 + 2;
const ll inf = 1ll << 60;
typedef pair<int, int> pii;
int lg[N];
struct TTree { /// get max value in range, add x in a range
vector<pair<ll, int>> st;
vector<ll> lz;
vector<pii> range;
int n, h; ll val;
pair<ll, int> top;
void init(int _n) {
n = _n; h = sizeof(int) * 8 - __builtin_clz(n);
st.resize(2 * n + 2, mp(0, 0));
lz.resize(2 * n + 2, 0);
for(int i = n - 1; i >= 0; --i) st[i + n].se = i;
}
void apply(int x, ll val) {
st[x].fi += val;
if(x < n) lz[x] += val;
}
inline pair<ll, int> Max(const pair<ll, int>& x, const pair<ll, int>& y) {
if(x.fi < y.fi) return y;
return x;
}
void build(int x) {
while(x > 1) {
x >>= 1;
st[x] = Max(st[x << 1], st[x << 1 | 1]);
st[x].fi += lz[x];
}
}
void push(int x) {
for(int i, s = h; s > 0; --s) {
i = x >> s;
if(lz[i] != 0) {
apply(x << 1, lz[i]);
apply(x << 1 | 1, lz[i]);
lz[i] = 0;
}
}
}
void upd(int l, int r, ll val) {
l += n, r += (n + 1);
int l0 = l, r0 = r;
for(; l < r; l >>= 1, r >>= 1) {
if(l & 1) apply(l ++, val);
if(r & 1) apply(-- r, val);
}
build(l0); build(r0 - 1);
}
ll diameter() {
top = st[1]; val = st[1].fi;
upd(range[top.se].fi, range[top.se].se, -top.fi);
val += max(st[1].fi, 0ll);
upd(range[top.se].fi, range[top.se].se, top.fi);
return val;
}
};
vector<TTree> it;
struct TEdge {
int u, v; ll w;
vector<int> it;
vector<pii> range;
} e[N];
vector<pii> adj[N];
ll W, dis[N];
int n, q, Time, head[N], in[N], out[N], sz[N], big[N];
bool del[N];
int find(int u) {
function<void(int, int)> dfs = [&](int u, int p) {
sz[u] = 1, big[u] = 0;
for(auto v: adj[u]) {
if(v.fi == p || del[v.fi]) continue;
dfs(v.fi, u);
sz[u] += sz[v.fi];
if(sz[v.fi] > sz[big[u]]) big[u] = v.fi;
}
};
dfs(u, -1);
int cen = u;
while(sz[big[cen]] * 2 >= sz[u] && big[cen]) cen = big[cen];
return cen;
}
multiset<ll, greater<ll>> ans;
void centroid(int u) {
int root = find(u);
it.push_back({});
function<void(int, int)> dfs = [&](int u, int p) {
in[u] = ++Time;
if(p == root) head[u] = u;
else if(p != -1) head[u] = head[p];
for(auto v: adj[u]) {
if(del[v.fi] || v.fi == p) continue;
dis[v.fi] = dis[u] + e[v.se].w;
it.back().range.pb(v.se, v.fi);
dfs(v.fi, u);
}
out[u] = Time;
};
Time = -2, dis[root] = 0;
dfs(root, -1); del[root] = 1;
if((int)it.back().range.size()) {
it.back().init((int)it.back().range.size());
for(auto& p: it.back().range) {
e[p.fi].it.pb((int)it.size() - 1);
e[p.fi].range.pb(in[p.se], out[p.se]);
it.back().upd(in[p.se], in[p.se], dis[p.se]);
p.fi = in[head[p.se]], p.se = out[head[p.se]];
}
ans.insert(it.back().diameter());
}
for(auto v: adj[root]) {
if(del[v.fi]) continue;
centroid(v.fi);
}
}
///40071305542068
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0), cout.tie(0);
#define Task "test"
if(fopen(Task".inp", "r")) {
freopen(Task".inp", "r", stdin);
freopen(Task".out", "w", stdout);
}
cin >> n >> q >> W;
for(int i = 1; i <= n; ++i) lg[i] = log2(i) + 1;
for(int i = 0; i < n - 1; ++i) {
cin >> e[i].u >> e[i].v >> e[i].w;
adj[e[i].u].pb(e[i].v, i);
adj[e[i].v].pb(e[i].u, i);
}
centroid(1); ll w, lst = 0;
for(int id, tree; q > 0; --q) {
cin >> id >> w;
id = ((ll)id + lst) % (n - 1);
w = (w + lst) % W;
for(int i = 0; i < e[id].it.size(); ++i) {
tree = e[id].it[i];
ans.erase(ans.find(it[tree].diameter()));
it[tree].upd((int)e[id].range[i].fi, (int)e[id].range[i].se, w - e[id].w);
ans.insert(it[tree].diameter());
}
e[id].w = w;
cout << (lst = *ans.begin()) << '\n';
}
}
