using namespace std;
int main()  { 
    double s,q=2,g=0;
    int k=0;
    cin >>s;
    for(s;s!=0;q=q*100/98){
    	s=s-q;
    	k++;
    	if(s<=0){
    		cout<<k;
    		return 0;
		}
	}
}