trick:
通过h存正图和反图
不一定所有点都可以到达终点
multiset的删除

error:
段错误的一个可能性:ll的运算用int存

#include<bits/stdc++.h>
//正图和反图,用head来区分即可
//指针不可以读sizeof
//忘了判断联通性了，不一定可以通过某个点去到终点
//删除multiset的时候的先find再删除
//段错误的一个可能性：ll写成了int
using namespace std;
using pii = pair<long long,int>;
using ll = long long;
const int N = 1e5+5;
const int M =4e5+3;
int n,m,q;
int e[M],nex[M],cnt;
ll w[M];
int h1[N],h2[N];
ll aa[N];
void add(int *head,int a,int b,ll c)
{
    e[cnt]=b,w[cnt]=c,nex[cnt]=head[a],head[a]=cnt++;
}
bool repeat[N];
ll dist1[N],dist2[N];
void dijkstra(ll *dist,int *head,int tttop)
{
    //sizeof dist返回指针大小,不要搞错了
    // memset(dist,0x3f,sizeof dist);
    memset(dist,0x3f,sizeof dist1);

    memset(repeat,0,sizeof repeat);
    multiset<pii> sset;
    dist[tttop]=0;
    sset.insert(make_pair(0,tttop));
    while(sset.size())
    {
        auto ttop=*(sset.begin());
        auto it = sset.begin();
        sset.erase(it);
        int u=ttop.second;
        if(repeat[u])continue;
        repeat[u]=true;
        for(int i=head[u];i!=-1;i=nex[i])
        {
            int v=e[i];
            ll w2=w[i];
            if(dist[v]>dist[u]+w2)
            {
                dist[v]=dist[u]+w2;
                sset.insert(make_pair(dist[v],v));
            }
        }
    }
}

int main()
{
    ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
    cin>>n>>m>>q;
    memset(h1,-1,sizeof h1);
    memset(h2,-1,sizeof h2);
    for(int i=1;i<=m;i++)
    {
        int u,v,c,d;
        cin>>u>>v>>c>>d;
        add(h1,u,v,c);
        add(h2,v,u,d);
    }
    multiset<ll> val;

    dijkstra(dist1,h1,1);
    dijkstra(dist2,h2,n);

    for(int v=1;v<=n;v++)
    {
        cin>>aa[v];
        //当前点兑换的最小金额数就是dist1[i]+ceil(dist2[i]/a[i]);
        if(dist1[v]!=0x3f3f3f3f3f3f3f3fll&&dist2[v]!=0x3f3f3f3f3f3f3f3fll)
        {
            //这里写成了int会导致段错误
            ll temp_val=dist1[v]+(dist2[v]+aa[v]-1)/aa[v];
            val.insert(temp_val);
        }
    }

    while(q--){
        int v;
        ll www;
        cin>>v>>www;
        if(dist1[v]!=0x3f3f3f3f3f3f3f3fll&&dist2[v]!=0x3f3f3f3f3f3f3f3fll)
        {
            auto era=val.find(dist1[v]+(dist2[v]+aa[v]-1)/aa[v]);
            val.erase(era);
        }
        aa[v]=www;
        if(dist1[v]!=0x3f3f3f3f3f3f3f3fll&&dist2[v]!=0x3f3f3f3f3f3f3f3fll)
            val.insert(1ll*dist1[v]+1ll*(dist2[v]+aa[v]-1)/aa[v]);
        cout<<(*(val.begin()))<<endl;
    }

    return 0;
}