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