#include<bits/stdc++.h>
using namespace std;
int main(){
    double n;
    int ans=0;
    double s=2;
    scanf("%lf",&n);
    while(1){
        if(n<=0) break;
        n-=s;
        s*=0.98;
        ans++;
    }
    printf("%d",ans);
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main(){
    double n;
    int ans=0;
    double s=2;
    scanf("%lf",&n);
    while(1){
        if(n<=0) break;
        n-=s;
        s*=0.98;
        ans++;
    }
    printf("%d",ans);
    return 0;
}