public class Sieve {
	static boolean[] sieve=new boolean[20002];//false if prime, true if not prime, first spot is 0 =useless

	public static void main(String[] args){
		Sieve mine=new Sieve();
		int input=10000;//must be between 1 and 10,000
		int ans=0;
		
		int pos;
		for (pos=2;pos<sieve.length;pos++){
			if (!sieve[pos]) mine.crossOut(pos);
		}
		
		
		for (int k=2;k<=input;k++){//starts at 2 because sophie numbers are greater than 1
			if (!sieve[k] && !sieve[(2*k)+1] ) ans+=1;
		}
		System.out.println(ans);
	}
	
	public void crossOut(int val){
		int origVal=val;
		val+=origVal;
		while (val<sieve.length){
			sieve[val]=true;
			val+=origVal;
		}
	}
}