#include<bits/stdc++.h>
#define int long long
#define ii pair<int,int>
using namespace std;
const int maxn = 1e5 + 5;
int n, q, W;
array<int, 2> qr[maxn];
vector<int> adj[maxn];
vector<array<int, 2>> edges;
struct sub1{
int dp[maxn][2], ans;
void dfs(int x = 1, int p = 1)
{
dp[x][0] = dp[x][1] = 0;
for (int id : adj[x])
{
int i = edges[id][0] - x, w = edges[id][1];
if (i == p) continue;
dfs(i, x);
if (dp[x][0] < dp[i][0] + w)
dp[x][1] = dp[x][0], dp[x][0] = dp[i][0] + w;
else dp[x][1] = max(dp[x][1], dp[i][0] + w);
}
ans = max(ans, dp[x][0] + dp[x][1]);
}
sub1()
{
for (int i = 1, last = 0; i <= q; i++)
{
int id = qr[i][0], w = qr[i][1];
id = (id + last) % (n - 1);
w = (w + last) % W;
edges[id][1] = w;
ans = 0;
dfs();
cout << (last = ans) << "\n";
}
}
};
void subtask1()
{
sub1 gold_voi;
}
void subtask3()
{
assert(0);
vector<int> a(n + 1);
set<pair<int,int>> s;
for (auto [u, v] : edges)
a[u - 1] = v,
s.emplace(v, u - 1);
for (int i = 1, last = 0; i <= q; i++)
{
int id = qr[i][0], w = qr[i][1];
id = (id + last) % (n - 1);
w = (w + last) % W;
int node = edges[id][0] - 1;
s.erase(s.find({a[node], node}));
a[node] = w;
s.emplace(a[node], node);
int ans = 0;
auto it = prev(s.end());
if (s.size())
ans += it -> first;
if (s.size() >= 2)
ans += prev(it) -> first;
cout << (last = ans) << "\n";
}
}
struct sub4{
int dp[maxn][2], mx[maxn], node[maxn];
int ans;
void dfs(int x = 1, int p = 1)
{
dp[x][0] = dp[x][1] = 0;
mx[x] = 0;
for (int id : adj[x])
{
int i = edges[id][0] - x, w = edges[id][1];
if (i == p) continue;
node[id] = x;
dfs(i, x);
if (dp[x][0] < dp[i][0] + w)
dp[x][1] = dp[x][0], dp[x][0] = dp[i][0] + w;
else dp[x][1] = max(dp[x][1], dp[i][0] + w);
mx[x] = max(mx[x], mx[i]);
}
mx[x] = max(mx[x], dp[x][0] + dp[x][1]);
}
void upd(int x)
{
if (x) return;
mx[x] = 0;
for (int id : adj[x])
{
int i = edges[id][0] - x, w = edges[id][1];
if (i == x / 2) continue;
if (i == x * 2)
dp[x][0] = max(dp[i][0], dp[i][1]) + w;
else dp[x][1] = max(dp[i][0], dp[i][1]) + w;
mx[x] = max(mx[x], mx[i]);
}
mx[x] = max(mx[x], dp[x][0] + dp[x][1]);
ans = max(ans, mx[x]);
upd(x / 2);
}
sub4()
{
dfs();
for (int i = 1, last = 0; i <= q; i++)
{
int id = qr[i][0], w = qr[i][1];
id = (id + last) % (n - 1);
w = (w + last) % W;
edges[id][1] = w;
ans = 0;
upd(node[id]);
cout << (last = ans) << "\n";
}
}
};
void subtask4()
{
// ass
sub4 gold_voi;
}
struct sub5{
int seg[4 * maxn], lz[4 * maxn], node[maxn], in[maxn], out[maxn], head[maxn];
int cnt = 0;
inline void add(int id, int val)
{
seg[id] += val;
lz[id] += val;
}
inline void down(int id)
{
if (lz[id] == 0) return;
add(id * 2, lz[id]);
add(id * 2 + 1, lz[id]);
lz[id] = 0;
}
void upd(int lx, int rx, int val, int id = 1, int l = 1, int r = n)
{
if (lx > r || l > rx) return;
if (lx <= l && r <= rx) return add(id, val);
int mid = (l + r) / 2;
down(id);
upd(lx, rx, val, id * 2, l, mid);
upd(lx, rx, val, id * 2 + 1, mid + 1, r);
seg[id] = max(seg[id * 2], seg[id * 2 + 1]);
}
int qry(int lx, int rx, int id = 1, int l = 1, int r = n)
{
if (lx > r || l > rx) return 0;
if (lx <= l && r <= rx) return seg[id];
int mid = (l + r) / 2;
down(id);
return max(qry(lx, rx, id * 2, l, mid), qry(lx, rx, id * 2 + 1, mid + 1, r));
}
void dfs(int x = 1, int p = 1, int w = 0, int top = -1)
{
in[x] = ++cnt;
head[x] = top;
for (int id : adj[x])
{
int i = edges[id][0] - x, w = edges[id][1];
if (i == p) continue;
int t = top;
if (t == -1)
t = i;
node[id] = i;
dfs(i, x, w, t);
}
out[x] = cnt;
upd(in[x], out[x], w);
}
sub5()
{
dfs();
vector<int> a(n + 1);
set<pair<int,int>> s;
for (int id : adj[1])
{
int i = edges[id][0] - 1;
a[i] = qry(in[i], out[i]);
s.emplace(a[i], i);
}
for (int i = 1, last = 0; i <= q; i++)
{
int id = qr[i][0], w = qr[i][1];
id = (id + last) % (n - 1);
w = (w + last) % W;
int x = node[id];
upd(in[x], out[x], w - edges[id][1]);
edges[id][1] = w;
x = head[x];
s.erase(s.find({a[x], x}));
a[x] = qry(in[x], out[x]);
s.emplace(a[x], x);
int ans = 0;
auto it = prev(s.end());
if (s.size())
ans += it -> first;
if (s.size() >= 2)
ans += prev(it) -> first;
cout << (last = ans) << "\n";
}
}
};
void subtask5()
{
sub5 gold_voi;
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
// freopen("test.inp", "r", stdin);
// freopen("AC.out", "w", stdout);
cin >> n >> q >> W;
int s3 = 1, s4 = 1;
for (int i = 1, u, v, w; i < n; i++)
{
cin >> u >> v >> w;
if (u > v) swap(u, v);
adj[u].emplace_back(edges.size());
adj[v].emplace_back(edges.size());
edges.push_back({u + v, w});
s3 &= (u == 1 || v == 1);
s4 &= (u * 2 == v || u * 2 + 1 == v);
}
for (int i = 1; i <= q; i++)
cin >> qr[i][0] >> qr[i][1];
if (max(n, q) <= 5000)
subtask1();
else if (s3)
subtask3();
else if (s4)
subtask4();
else subtask5();
}
