import java.io.PrintWriter
import java.math.BigInteger

val cout = PrintWriter(System.out)

fun readLn() = readLine()!!
fun readInt() = readLn().toInt()
fun readLong() = readLn().toInt()
fun readDouble() = readLn().toDouble()
fun readStrings() = readLn().split(" ")
fun readInts() = readStrings().map { it.toInt() }
fun readLongs() = readStrings().map { it.toLong() }
fun readDoubles() = readStrings().map { it.toDouble() }

fun main(args: Array<String>) {
    var (t, a, b) = readStrings().map { it.toBigInteger() }
    t -= BigInteger.ONE
    println(t/a + t/b - t/(a*b/a.gcd(b))+ BigInteger.ONE)
}