import java.math.*;
import java.util.*;

class Main {
	static int gcd(int dai,int syou){
		if(syou==0) return dai;
		else return gcd(syou, dai%syou);
		
	}
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int x = sc.nextInt();
		int y=sc.nextInt();
		int ans=1;
		for(int i=1;i<=x/2;i++){
			ans=Math.max(ans, gcd(x-i, i));
		}
		System.out.println(ans);
	}
}