#include 
#include 
#include 
#include 
#include 
//#include 
using namespace std;






int main()
{
    int n;
    cin>>n;
    vector < pair > v;
    int x,y;
    for(int i=0;i>x>>y;
        v.push_back(make_pair(x,y));
    }
    vector < pair > g[n];




   vector visited(n,false);
    vector dis(n,-2e9);
    for(int i=0;i > pq;
    pq.push(make_pair(0,0));




   while(!pq.empty())
    {
        pair c=pq.top();

        pq.pop();


       if(visited[c.second])
        {
            continue;
        }
        visited[c.second]=true;
        for(int i=0;idis[s])
            {
                pq.push(make_pair(c.first+t, s));
                dis[s]=c.first+t;
            }
        }
    }
    cout<<-dis[n-1]<