#include<stdio.h>

int main()

{

int a,b,c,d;

scanf("%d%d%d%d",&a,&b,&c,&d);

int i,j,count;

for(i=a;i<=a*d;i+=a)

{for(j=b;j<=b*d;j+=b)

{if(i==j)continue;

count++;  

}

for(j=c;j<=c*d;j+=c)

{if(i==j)continue;

count++;  

}

count++;}

for(i=b;i<=b*d;i+=b)

{ for(j=c;j<=c*d;j+=c)

{if(i==j)

count--;  

}

}

printf("%d",count-2*d*(d-1));

return 0;

}