import java.util.*;
import java.io.*;

public class Main {
	public static void main (String[] args) throws Exception{
    	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    	String[] first = br.readLine().split(" ", 3);
    	long t = Long.parseLong(first[0]) - 1;
    	long a = Long.parseLong(first[1]);
     	long b = Long.parseLong(first[2]);
     	long ans = t / a + t / b - t / getLCM(a, b) + 1;
     	System.out.println(ans);
    }
    
    static long getLCM(long a, long b) {
        long gcd = getGCD(a, b);
        long ans = a / gcd;
        if (Long.MAX_VALUE / b <= ans) {
            return Long.MAX_VALUE;
        } else {
            return ans * b;
        }
    }
    
    static long getGCD(long a, long b) {
        if (a % b == 0) {
            return b;
        } else {
            return getGCD(b, a % b);
        }
    }
}