import java.io.* ;
public class robot {
    static double spin(double[] x, double[] y, int a, int b, int c, int d) {
	return 180 / Math.PI *
	    Math.abs(Math.IEEEremainder(Math.atan2(y[b]-y[a], x[b]-x[a])-
					Math.atan2(y[d]-y[c], x[d]-x[c]),
					2*Math.PI)) ;
    }
    static double d(double[] x, double[] y, int a, int b) {
	return Math.sqrt((x[a]-x[b])*(x[a]-x[b])+(y[a]-y[b])*(y[a]-y[b])) ;
    }
    public static void main(String[] args) throws Exception {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in)) ;
	while (true) {
	    String s = br.readLine() ;
	    String[] f = s.split(" ") ;
	    double r = Double.parseDouble(f[0]) ;
	    int n = Integer.parseInt(f[1]) ;
	    if (n < 0)
		return ;
	    double x[] = new double[n] ;
	    double y[] = new double[n] ;
	    double t[][][] = new double[n][n][n] ;
	    for (int i=0; i<n; i++) {
		s = br.readLine() ;
		f = s.split(" ") ;
		x[i] = Double.parseDouble(f[0]) ;
		y[i] = Double.parseDouble(f[1]) ;
		for (int j=0; j<n; j++) {
		    t[i][j][i] = 1e30 ;
		    t[i][i][j] = 1e30 ;
		}
	    }
	    t[0][0][n-1] = 0 ;
	    for (int i=1; i<=n-1; i++) {
		t[0][0][i] = spin(x, y, 0, n-1, 0, i) ;
		t[0][i][0] = spin(x, y, 0, n-1, i, 0) ;
	    }
	    while (true) {
		boolean changed = false ;
		for (int i=0; i<n; i++)
		    for (int j=0; j<n; j++)
			if (d(x, y, i, j) <= r && t[i][i][j] < 1e20) {
			    double na = t[i][i][j] + d(x, y, i, j) ;
			    if (na < t[j][i][j]) {
				changed = true ;
				for (int k=0; k<n; k++)
				    if (k != j) {
					t[j][j][k] = Math.min(t[j][j][k],
						na + spin(x, y, i, j, j, k)) ;
					t[j][k][j] = Math.min(t[j][k][j],
                                                na + spin(x, y, i, j, k, j)) ;
				    }
			    }
			}
		if (!changed)
		    break ;
	    }
	    double ba = 1e30 ;
	    for (int i=0; i<n; i++)
		if (t[n-1][i][n-1] < ba)
		    ba = Math.round(t[n-1][i][n-1]) ;
	    if (ba < 1e30)
		System.out.println((int)ba) ;
	    else
		System.out.println("impossible") ;
	}
    }
}