#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;}

int h[100001];

main(){
	char*rp=mmap(0l,7l*2*100001,1,2,0,0ll);
	while(*rp++!=10);
	int z=-2;
	do{
		RD(a);
		int v=++h[a];
		z+=(v==1)-(v==2);
	}while(*rp);
	printf("%d",z);
}