#include<bits/stdc++.h> 
using namespace std; 

int main(){ 
	int i = 5;
	long long s = 0;
	int c = 0;
	while(1==1){
		s=pow(2,pow(2,i));
		for(int j = 2;j <= sqrt(s);j++){
			if(s % j == 0){
				c++;
				break;
			}
		}
		if(c != 0){
			cout<<i;
			break;	
		}
		i++;
	}
	return 0;
} 
/**************************************************************
	Problem: 1352
	User: admin
	Language: C++
	Result: Accepted
	Time:4 ms
	Memory:2072 kb
****************************************************************/