#include <fstream>
#include <vector>
#define NMAX 1500
#define Infinit 100000
using namespace std;
ifstream fin("bf.in");
ofstream fout("bf.out");
struct varf
{
    int x;
    int c;
};
vector<varf>G[NMAX];
int d[NMAX],cmin[NMAX],viz[NMAX],prec[NMAX],vfmin,p;
int nr[NMAX],n;
void citire()
{
    fin>>n>>p;
    int i,a,b;
    varf arc;
    while(fin>>a)
    {
        fin>>arc.x>>arc.c;
        G[a].push_back(arc);
    }
}
void afisare()
{
    int i;
    for(i=0;i<=G[1].size();i++)
    {
        fout<<G[1][i];
    }
}
int main()
{
    for(i=1;i<=n;i++)
    {
        cmin[i]=INFINIT;
        prec[i]=p;
    }
    cmin[p]=0;
    prec[p]=0;
    C.push(p);
    while(!C.empty())
    {
        x=C.front();C.pop();
        for(i=0;i<G[x].size();i++)
        {
            if(cmin[G[vf][i].x]>cmin[vf]+G[vf][i].c)
            {
                cmin[G[vf][i].x]=cmin[vf]+G[vf][i].c;
                prec[G[vf][i].x]=vf;
                nr[G[vf][i].x]++;
                if(nr[G[vf][i].x>=n)
                {
                    fout<<"Nu e";
                    fout.close();
                    return 0;
                }
                C.push(G[vf][i].x);
            }
        }
    }
    afisare();
    fin.close();
    fout.close();
    return 0;
}