#include<iostream>

#include<cmath>

#include<cstring>

#include<queue>

#include<vector>

#include<cstdio>

#include<algorithm>

#include<map>

#include<set>

#define rep(i,e) for(int i=0;i<(e);i++)

#define rep1(i,e) for(int i=1;i<=(e);i++)

#define repx(i,x,e) for(int i=(x);i<=(e);i++)

#define X first

#define Y second

#define PB push_back

#define MP make_pair

#define mset(var,val) memset(var,val,sizeof(var))

#define scd(a) scanf("%d",&a)

#define scdd(a,b) scanf("%d%d",&a,&b)

#define scddd(a,b,c) scanf("%d%d%d",&a,&b,&c)

#define pd(a) printf("%d\n",a)

#define scl(a) scanf("%lld",&a)

#define scll(a,b) scanf("%lld%lld",&a,&b)

#define sclll(a,b,c) scanf("%lld%lld%lld",&a,&b,&c)

#define IOS ios::sync_with_stdio(false);cin.tie(0)

#define lc idx<<1

#define rc idx<<1|1

#define rson mid+1,r,rc

#define lson l,mid,lc

using namespace std;

typedef long long ll;

template <class T>

void test(T a){cout<<a<<endl;}

template <class T,class T2>

void test(T a,T2 b){cout<<a<<" "<<b<<endl;}

template <class T,class T2,class T3>

void test(T a,T2 b,T3 c){cout<<a<<" "<<b<<" "<<c<<endl;}

const int inf = 0x3f3f3f3f;

const ll INF = 0x3f3f3f3f3f3f3f3fll;

const ll mod = 1e9+;

int T;

void testcase(){

    printf("Case %d: ",++T);

}

const int MAXN = 1e5+;

const int MAXM = ;

int main() {

#ifdef LOCAL

    freopen("data.in","r",stdin);

#endif // LOCAL

    double l,n,c;

    while(~scanf("%lf%lf%lf",&l,&n,&c)){

        if(l<&&n<&&c<) break;

        double low=0.0,high=asin(1.0),mid;

        double L=(+n*c)*l;

        while(high-low>1e-){

            mid=(high+low)/;

            if(L*sin(mid)<=l*mid) high=mid;

            else low=mid;

        }

        printf("%.3f\n",l/*tan(low/));

    }

    return ;

}