#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 5;
int n,k,q,a[N],cnt,ans;
bool b[N];
deque<int> d[N];
void h(int x,int y)
{
    if ((a[x] + y) % k != 0)
    {
        ans++;
    }
    for (int i = 0;i < d[x].size();i++)
    {
        h(d[x][i],y + k - ((a[x] + y) % k));
    }
}
int main()
{
    freopen("tioj_outplay.in","r",stdin);
    freopen("tioj_outplay.out","w",stdout);
    cin >> n >> k >> q;
    for (int i = 1;i <= n;i++)
    {
        cin >> a[i];
    }
    for (int i = 1,x,y;i < n;i++)
    {
        cin >> x >> y;
        b[y] = 1;
        d[x].push_back(y);
    }
    for (int i = 1;i <= n;i++)
    {
        if (!b[i])
        {
            cnt = i;
            break;
        }
    }
    for (int i = 1,p,m;i <= q;i++)
    {
        ans = 0;
        cin >> p >> m;
        a[p] = m;
        h(cnt,0);
        cout << ans << endl;
    }
    return 0;
}