double f(double x){
return cos(2*pi*x*x*x);
}
void main(void){
long n;
double x0 = 0;
double x1 = 1;
double ymin = 1.0e20;
double xmin = x0;
double x, y, dx;
cin >> n;
x = x0;
dx = (x1 - x0)/n;
for(long i=0; i<n; i++){
y = f(x);
if(y < ymin){
ymin = y;
xmin = x;
}
x += dx;
}
cout << xmin << endl;
}