#include <iostream>
#include <fstream>
#include <cmath>
using namespace std;
ifstream f("arbori_in_graf.in");
ofstream g("arbori_in_graf.out");
const double EPS = 1E-9;
double a[51][51],det;
int n,m,x,y,grad[51],i,j,k;
int main()
{
    f>>n>>m;
    while(m--)
    {
        f>>x>>y;
        x--;
        y--;
        a[x][y]--;
        a[y][x]--;
        grad[x]++;
        grad[y]++;
    }
    for(i=0;i<n;i++)
    {
        a[i][i]=grad[i];
    }
    n--;
    det = 1;
    for (i=0; i<n; ++i) {
    k = i;
    for (j=i+1; j<n; ++j)
        if (abs (a[j][i]) > abs (a[k][i]))
            k = j;
    if (abs (a[k][i]) < EPS) {
        det = 0;
        break;
    }
    swap (a[i], a[k]);
    if (i != k)
        det = -det;
    det *= a[i][i];
    for (int j=i+1; j<n; ++j)
        a[i][j] /= a[i][i];
    for (j=0; j<n; ++j)
        if (j != i && abs (a[j][i]) > EPS)
            for (k=i+1; k<n; ++k)
                a[j][k] -= a[i][k] * a[j][i];
    }
    g << det;
    return 0;
}