#include<bits/stdc++.h>
using namespace std;
bool fl=1,pd=1;
typedef __int128 LL;
const int N=1e5+5;
int n;
priority_queue<LL>q1,q2;
LL t[N<<2],lz[N<<2];
void update(int p)
{
    t[p]=max(t[p<<1],t[p<<1|1]);
}
void pushlz(int p,LL z)
{
    t[p]+=z;
    lz[p]+=z;
}
void lzdown(int p)
{
    pushlz(p<<1,lz[p]);
    pushlz(p<<1|1,lz[p]);
    lz[p]=0;
}
void change(int p,int l,int r,int x,int y,LL z)
{
    if(x<=l&&r<=y)
    {
        pushlz(p,z);
        return ;
    }
    lzdown(p);
    int mid=l+r>>1;
    if(x<=mid)
    {
        change(p<<1,l,mid,x,y,z);
    }
    if(mid+1<=y)
    {
        change(p<<1|1,mid+1,r,x,y,z);
    }
    update(p);
}
LL query(int p,int l,int r,int x,int y)
{
    if(x<=l&&r<=y)
    {
        return t[p];
    }
    int mid=l+r>>1;
    LL ret=0;
    lzdown(p);
    if(x<=mid)
    {
        ret=max(ret,query(p<<1,l,mid,x,y));
    }
    if(mid+1<=y)
    {
        ret=max(ret,query(p<<1|1,mid+1,r,x,y));
    }
    return ret;
}
struct Edge{
    int v,nxt,id;
    LL c;
}e[N<<1];
int p[N];
LL edge[N];
int h[N],tot1;
void addEdge(int u,int v,LL c,int id)
{
    tot1++;
    e[tot1].v=v;e[tot1].nxt=h[u];
    e[tot1].c=c;e[tot1].id=id;
    h[u]=tot1;
}
int fa[N];
LL len[N];
LL ans,d[N];
void dfs0(int u)
{
    LL zd=0,cd=0;
    for(int i=h[u];i;i=e[i].nxt)
    {
        int v=e[i].v;
        if(v==fa[u])
        {
            continue;
        }
        p[e[i].id]=v;edge[v]=e[i].c;
        fa[v]=u;
        dfs0(v);
    }
}
void add(LL x)
{
//    cout<<"add("<<x<<")\n";
    q1.push(x);
}
void del(LL x)
{
//    cout<<"del("<<x<<")\n";
    q2.push(x);
}
LL get_top()
{
//    cout<<q1.top()<<'#'<<q2.top()<<endl;
    while(!q1.empty()&&!q2.empty()&&q1.top()==q2.top())
    {
    //    cout<<q1.top()<<'^'<<q2.top()<<endl;
        q1.pop();q2.pop();
    }
//    assert(q1.empty()==0);
    if(q1.empty())
    {
        return -1;
    }
    return q1.top();
}
void calc(int u)
{
    d[u]=0;
    LL zd=0,cd=0;
    del(len[u]);
    for(int i=h[u];i;i=e[i].nxt)
    {
        int v=e[i].v;
        if(v==fa[u])
        {
            continue;
        }
        d[u]=max(d[u],d[v]+edge[v]);
        if(zd<d[v]+edge[v])
        {
            cd=zd;
            zd=d[v]+edge[v];
        }else if(cd<d[v]+edge[v])
        {
            cd=d[v]+edge[v];
        }
    }
    len[u]=zd+cd;
    add(zd+cd);
}
void dfs(int u)
{
    d[u]=0;
    LL zd=0,cd=0;
    for(int i=h[u];i;i=e[i].nxt)
    {
        int v=e[i].v;
        if(v==fa[u])
        {
            continue;
        }
        fa[v]=u;
        dfs(v);
        d[u]=max(d[u],d[v]+edge[v]);
        if(zd<d[v]+edge[v])
        {
            cd=zd;
            zd=d[v]+edge[v];
        }else if(cd<d[v]+edge[v])
        {
            cd=d[v]+edge[v];
        }
    }
    len[u]=zd+cd;
    add(len[u]);
}
LL dep[N];
int dfn[N],idx,sz[N],hd[N];
void dfs1(int u)
{
    dfn[u]=++idx;sz[u]=1;
    change(1,1,n,dfn[u],dfn[u],dep[u]);
    for(int i=h[u];i;i=e[i].nxt)
    {
        int v=e[i].v;
        if(v==fa[u])
        {
            continue;
        }
        dep[v]=dep[u]+edge[v];
        if(u==1)
        {
            hd[v]=v;
        }else{
            hd[v]=hd[u];
        }
        dfs1(v);
        sz[u]+=sz[v];
    }
}
int main()
{
    int u,v,id,Q;
    LL w,c;
    scanf("%d%d%lld",&n,&Q,&w);
    for(int i=1;i<n;i++)
    {
        scanf("%d%d%lld",&u,&v,&c);
        addEdge(u,v,c,i-1);
        addEdge(v,u,c,i-1);
        if(u>1&&v>1)
        {
            fl=0;
        }
        if(u/2!=v&&v/2!=u)
        {
            pd=0;
        }
    }
    ans=0;
    dfs0(1);
    bool fl1=(n>5000&&pd==0);
    if(0)
    {
        for(int i=2;i<=n;i++)
        {
            q1.push(edge[i]);
        }
    }else if(fl1){
        dfs1(1);
        for(int i=h[1];i;i=e[i].nxt)
        {
            int v=e[i].v;
            add(query(1,1,n,dfn[v],dfn[v]+sz[v]-1));
        }
    }else{
        dfs(1);
    }
    ans=0;
    while(Q--)
    {
        scanf("%d%lld",&id,&c);
        id+=ans%(n-1);id%=n-1;
        c+=ans%w;c%=w;
        if(fl&&0)
        {
            del(edge[p[id]]);
            add(c);
        }
        if(fl1)
        {
            int x=hd[p[id]];
            del(query(1,1,n,dfn[x],dfn[x]+sz[x]-1));
            change(1,1,n,dfn[p[id]],dfn[p[id]]+sz[p[id]]-1,c-edge[p[id]]);
            add(query(1,1,n,dfn[x],dfn[x]+sz[x]-1));
        }
        edge[p[id]]=c;
    //    cout<<id<<' '<<p[id]<<'*'<<c<<endl;
        if(fl1==0){
            for(int u=fa[p[id]];u;u=fa[u])
            {
                calc(u);
            }
            ans=get_top();
        }else{
        LL cur=get_top();del(cur);
        LL cur1=get_top();
        if(cur1==-1)
        {
            ans=cur;
        }else{
            ans=cur+cur1;
        }
        add(cur);
        }
        printf("%lld\n",(long long)ans);
    }
    return 0;
}