#include <fstream>
using namespace std;
ifstream fin("date.in");
ofstream fout("date.out");

int a[50][50],x[50],p[50],n,m,gasit;

void citire()
{
    int i,j;
    fin>>n>>m;
    while(fin>>i>>j) a[i][j]=a[j][i]=1;

}

int bun(int k)
{
   if(k>1) if(a[x[k]][x[k-1]]==0) return 0;
   if(k==n) if(a[x[1]][x[n]]==0) return 0;
   return 1;
}

void back(int k)
{
    if(!gasit)
    for(int i=1;i<=n;i++)
      if(!p[i])
      {
          x[k]=i; p[i]=1;
          if(bun(k)) if(k==n) gasit=1;
                     else back(k+1);
          p[i]=0;
      }

}
int main()
{
    citire();
    back(1);
    if(gasit) fout<<"da";
    else fout<<"nu";
    fin.close();
    fout.close();
    return 0;
}