#include<bits/stdc++.h>
using namespace std;
using ll = long long;
 
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define reps(i, s, n) for (int i = (s); i < (int)(n); ++i)
#define ZERO {puts("0"); return 0;}
#define NO {puts("No"); return 0;}
#define ALL(obj) begin(obj), end(obj)
#define pb push_back
#define vi vector<int>
#define vvi vector<vector<int>>
#define vl vector<ll>
#define vvl vector<vl>
 
template<class T> void chmin(T& a, T b) { if (a > b) a = b; }
template<class T> void chmax(T& a, T b) { if (a < b) a = b; }

int const X = 101;
double dp[X][X][X];

int main() 
{
	int a, b, c; cin >> a >> b >> c;

	for (int i = 99; i >= a; --i)
		for (int j = 99; j >= b; --j)
			for (int k = 99; k >= c; --k)
			{
				double now = 0;
				now += dp[i+1][j][k] * i;
				now += dp[i][j+1][k] * j;
				now += dp[i][j][k+1] * k;
				dp[i][j][k] = now / (i+j+k) + 1;
			}
	printf("%.10f\n", dp[a][b][c]);
}

#include <bits/stdc++.h>
 
using namespace std;
 
int main()
{
 long  double  r,x,y;
   long double  d;
    cin>>r>>x>>y;
    d=sqrt((x*x)+(y*y));
    
    if(d==r)
    cout<<1;
    else
    if(d<=(2*r))
    cout<<2;
    else
    cout<<ceil(d/r);
    
    return 0;
}