#include <cstdio>
#include <algorithm>
#define rep( i, n, m ) for(int i = ( n ); i < ( m ); i++)

typedef long long int ll;

int main( void ){
	ll n, a, b;
	if (!scanf( "%lld %lld %lld", &n, &a, &b ))
		return 0;
	ll sum = 0;
	n--;
	sum += n / a + n / b + 2;
	ll gcd = std::__gcd( a, b );
	sum -= ( n * gcd / a / b ) + 1;
	printf( "%lld\n", sum );
	return 0;
}