#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")

char*mmap();
#define RD(v) int v=0;{int c;while(c=*rp++-48,c>=0)v=v*10+c;}

#define NB 18
int m[1<<NB];

main(){
	int z=0;
	int t=time(0)|1;

	char*rp=mmap(0l,1100l<<10,1,2,0,0ll);
	while(*rp++!=10);
	do{
		RD(a);
		long b=(long)t*a;
		int h=b&(1<<NB)-1;
		int s=b>>NB|1;
		while(1){
			if(m[h]==0){
				m[h]=a<<1;
				++z;
				break;
			}
			if(m[h]>>1==a){
				z-=~m[h]&1;
				m[h]|=1;
				break;
			}
			h=(h+s)&(1<<NB)-1;
		}
	}while(*rp);

	char wbuf[16],*wp=wbuf+16;
	while(*--wp=z%10+48,z/=10);
	write(1,wp,wbuf+16-wp);
	_exit(0);
}