#include
#include
using namespace std;
int main(){
int n,a[20]={0},i=0,b[100];
memset(b,false,sizeof(b));
while(cin>>n){
if(n==0)
{
int nu=0;
for(int j=0;j
if(a[j]%2==0){
if(b[a[j]/2]==true) nu++;
}
}
cout<<nu<<endl;
memset(a,0,sizeof(a));i=0;
memset(b,false,sizeof(b));
continue;
}
else if(n==-1) break;
else{
}
}
return 0;
}