#include <iostream>
#include <math.h>
#define cmp(a, b) (a += b, b = a - b, a -= b)
using namespace std;

int main(){
    double x, y, h;
    cin >> x >> y >> h;
    if (x > y) cmp(x, y);
    h /= 1000;
    
    int times = 0, i;
    for(i = 1; i < x / h; i *= 4) times += 1;
    int tmp = times;
    for(i = 1; i < y / (h * pow(2.0, tmp)); i *= 4) times += 1;

    cout << times << endl;

    return 0;
}