Tower<Dijkstra>

#include <bits/stdc++.h>
using namespace std;
int main(){
    int W,V,E,fr,to;
    scanf("%d%d%d",&W,&V,&E);
    vector<int> v[V+10];
    while(E--){
        scanf("%d%d",&fr,&to);
        v[fr].push_back(to);
    }
    vector<int> dis(V+10,2e9);
    vector<bool> visited(V+10,false);
    priority_queue<pair<int,int>,vector<pair<int,int>>,greater<pair<int,int>>> pq;
    pq.push({0,1});
    dis[1]=0;
    int mx=1;
    while(!pq.empty()){
        int curr=pq.top().second;
        pq.pop();
        visited[curr]=true;
        for(auto x:v[curr]){
            if(!visited[x]&&dis[x]>dis[curr]+1&&W>=dis[curr]+1){
                mx=max(mx,x);
                dis[x]=dis[curr]+1;
                pq.push({dis[x],x});
            }
        }
    }
    printf("%d",mx);
}