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

char*mmap();
#define rd_skip() while(*rp++>=48)

main(){
	char*rp=mmap(0l,1l<<25,1,2,0,0ll);
	rd_skip();

	long a=*rp; rp+=2;
	long b=*rp; rp+=2;
	long c=*rp; rp+=2;
	if(b==a||c==b||c==a){
		write(1,"0",1);
		_exit(0);
	}
	while(*rp){
		long d=*rp; rp+=2;
		long e=*rp; rp+=2;
		if(d!=b||e!=a){
			write(1,"0",1);
			_exit(0);
		}
		a=c;
		c=e;
	}
	c=(c+b*2)%3+48;
	write(1,&c,1);
	_exit(0);
}