#include<iostream>
#include<string>
using namespace std;

string calPlus( string a, string b )
{
    for( int i = a.size() - 1; i >= 1; i-- )
        a[i] += b[i] - '0';
    for( int i = a.size() - 1; i >= 1; i-- )
        if( a[i] - '0' > 9 )
        {
            a[i] -= 10;
            a[i-1]++;
        }
    int t = 0;
    while( a[t] == '0' )
        t++;
    return a.substr( t, a.size() );
}

int compareString( string a, string b )
{
    if( a.size() > b.size() )
        return 0;
    else if( a.size() < b.size() )
        return 1;
    else
    {
        for( int i = 0; i < a.size(); i++ )
        {
            if( a[i] > b[i] )
                return 0;
            else if( a[i] < b[i] )
                return 1;
            else;
        }
    }
    return 3;
}

int main()
{
    int cnt = 0;
    string s, t = "1";

    cin >> s;

    while( compareString( t, s ) != 0 )
    {
        t = calPlus( "0" + t, "0" + t );
        cnt++;
    }

    cout << cnt << endl;

    return 0;
}
