#include <iostream> 
   
  #include <stdlib.h> 
   
  #include <math.h> 
  using namespace std; 
   
  #define PI 3.14 
   
  #define E 2.71 
   
  int main(void) 
  { 
      double x; 
  cout << "x'e deger veriniz: "; 
  cin >> x ; 
  double y; 
  y = exp(-PI*x); 
  cout << "y: " << y << endl; 
  return EXIT_SUCCESS; 
  }