看不出哪错了，怎么输什么都是1

#include<stdio.h>
int main()
{
	double s;
	double length=2.0;
	int i=0;
	scanf("%.f",&s);
	while(s>0)
	{
		s-=length;
		length*=0.98;
		i+=1;
	}
	printf("%d",i);
	return 0;
}