#include <stdio.h>

int M,N;
int a[100][100];
int nr[100];
int distanta[100];
int sir[100],nrsir;

void CitesteDate(void){
  FILE *f=fopen("graf.in","rt");
  int x,y;
  fscanf(f,"%d%d",&N,&M);
  for (int i=0;i<M;i++){
    fscanf(f,"%d%d",&x,&y);
    x--;
    y--;
    a[x][nr[x]++] = y;
    a[y][nr[y]++] = x;
  }
  fclose(f);
}

void Initializare(void){
  sir[0]=0;
  nrsir=1;
  distanta[0]=0;
  for (int i=1;i<N;i++)
    distanta[i]=-1;
}

void Viziteaza(int x, int y){
  distanta[y]=distanta[x]+1;
  sir[nrsir++]=y;
}

void DeterminaSolutia(void){
  Initializare();
  for (int i=0;i<nrsir;i++){
    for (int j=0;j<nr[sir[i]];j++)
      if (distanta[a[sir[i]][j]]==-1)
	Viziteaza(sir[i],a[sir[i]][j]);
  }
}

void ScrieSolutia(void){
  FILE *f=fopen("graf.out","wt");
  fprintf(f,"%d",sir[N-1]);
  fclose(f);
}

void main(void){
  CitesteDate();
  DeterminaSolutia();
  ScrieSolutia();
}