#include<bits/stdc++.h>
#define int long long
#define ii pair<int,int>
using namespace std;
const int maxn = 2e5 + 5;
int n, q, W;
array<int, 2> qr[maxn];
vector<int> adj[maxn];
vector<array<int, 2>> edges;
int lz[4 * maxn], b[maxn], in[maxn], out[maxn];
int cnt = 0;
struct node{
int a, b, c, ab, bc, abc;
node(int val = 0)
{
a = b = c = ab = bc = abc = val;
}
node operator + (node x) const
{
node z;
if (a == -1e18) return x;
if (x.a == -1e18) return (*this);
z.a = max(a, x.a);
z.b = max(b, x.b);
z.c = max(c, x.c);
z.ab = max({ab, x.ab, a + x.b});
z.bc = max({bc, x.bc, b + x.c});
z.abc = max({abc, x.abc, ab + x.c, a + x.bc});
return z;
}
};
node seg[4 * maxn];
inline void add(int id, int val)
{
seg[id].a += val;
seg[id].b -= 2 * val;
seg[id].c += val;
seg[id].ab -= val;
seg[id].bc -= 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 * 2)
{
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] = seg[id * 2] + seg[id * 2 + 1];
}
void dfs(int x = 1, int p = 1, int w = 0)
{
in[x] = out[x] = ++cnt;
for (int id : adj[x])
{
int i = edges[id][0] - x, w = edges[id][1];
if (i == p) continue;
b[id] = i;
dfs(i, x, w);
out[x] = ++cnt;
}
upd(in[x], out[x], w);
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
// freopen("test.inp", "r", stdin);
// freopen("test.out", "w", stdout);
cin >> n >> q >> W;
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});
}
dfs();
for (int i = 1, last = 0; i <= q; i++)
{
int id, w;
cin >> id >> w;
id = (id + last) % (n - 1);
w = (w + last) % W;
int x = b[id];
upd(in[x], out[x], w - edges[id][1]);
edges[id][1] = w;
cout << (last = seg[1].abc) << "\n";
}
}
