#include<stdio.h>
int main() {
	int i = 1;
	float m = 2.0;
	float ret = 1.0;
	int a = 0;
	scanf("%d", &a);	
		while(ret<=a)
		{
			ret = ret+ 1.0 / m;
			m++;
			i++;
		}
	printf("%d\n", i);
	return 0;
}