#include<stdio.h>
int main()
{
    float a;
    double b=2;
    double c=2;
    int count=1;
    scanf("%f",&a);
    if(a>=b){
    while(b<=a){
        c=c*0.98;
        b=b+c;
        count++;
    }
    printf("%d",count);
    }else if(a<b){
    printf("1");
    }
    return 0;
}