#include<stdio.h>
int main(){
	long int N,A,B,count=0;
	scanf("%lf %lf %lf",&N,&A,&B);
	for(long int i=1;i<=N;i++){
		if((i%A!=0)&&(i%B!=0)){
			count++;
		}
	}
	printf("%f",count);
	return 0;
}