9bac 43

#include <iostream>

using namespace std;

int main() {

 unsigned n,a,b,nrok,x;
  nrok=0;
 cout<<"n=";cin>>n;
 cout<<"a=";cin>>a;
 cout<<"b=";cin>>b;
 for (x=a;x<=n;x+=a)
 {
    if (x%b!=0)
     nrok++;
 }
 cout<<nrok;
 return 0;
}