#include <iostream>
#include <sstream>
#include <string>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <cassert>

using namespace std;

#define FOR(i,k,n) for(int i=(k); i<(int)n; ++i)
#define REP(i,n) FOR(i,0,n)
#define FORIT(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)

template<class T> void debug(T begin, T end){ for(T i = begin; i != end; ++i) cout<<*i<<" "; cout<<endl; }

typedef long long ll;
const int INF = 100000000;
const double EPS = 1e-8;
const int MOD = 1000000007;
int P, Q, R;
double getx(double t){
  return (double)(P - Q) * cos(t) + (double)R * cos(t * (P - Q) / Q);
}
double dx(double t){
  return (double)(P - Q) * (-sin(t)) + (double)R * (P - Q) / Q * (-sin(t * (P - Q) / Q));
}
double gety(double t){
  return (double)(P - Q) * sin(t) - (double)R * sin(t * (P - Q) / Q);
}
double dy(double t){
  return (double)(P - Q) * (cos(t)) - (double)R * (P - Q) / Q * (cos(t * (P - Q) / Q));
}
double dist(double x1, double y1, double x2, double y2){
  return sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1));
}

int main(){
  while(cin>>P>>Q>>R && P){
    int time = -1;
    for(int k = 1; ; k++){
      if(R == 0){
        time = 1;
        break;
      }
      if(k * (P - Q) % Q == 0){
        time = k;
        break;
      }
    }
    const int ITER = 1000000;
    const double delta = 2.0 * time * M_PI / ITER;
    double ans = 0;
    REP(iter, ITER){
      double t = delta * iter;
      ans += sqrt(dx(t) * dx(t) + dy(t) * dy(t)) * delta;
    }
    printf("%.2f\n", ans + EPS);
  }
  return 0;
}