class Matek{
    private Matek(){}
    public static double abs(double x){
        if(x>=0)
            return x;
        else 
            return x * -1;
    }
    public static float abs(float x){
        if(x>=0)
            return x;
        else 
            return x * -1;
    }
    public static int abs(int x){
        if(x>=0)
            return x;
        else 
            return x * -1;
    }
    public static long abs(long x){
        if(x>=0)
            return x;
        else 
            return x * -1;
    }
    public static double ceil3(double x){
        if((x - (long)x)>0){
            return  (double)(long)x+1;
        }else{
            return  (double)(long)x;
        }       
    }
    public static long round(double x){
        if(x>0)
            return (long) (x + 0.5);
        if(x<0)
            return (long) (x - 0.5);
        return 0;
    }
    public static double floor(double x){
        if(x<0){
            if((double)(long)x ==x){
                return (long)x;
            }else{
                return (long)x-1;
            }
        }else{
            return (long)x;
        }
    }
    public static double pow(double a, double b){
        if(b == 0){
            return 1;
        }
        if(b==1){
            return a;
        }
        double tmp=1;
        for(int i=0;i<b;i++){
            tmp *= a;
        }
        return tmp;
    }
    public static int fact(int x){
        int factor = 1;
        for(int i=0;i<x;i++){
            factor *= i + 1;
        }       
        return factor;
    }
    public static double sin(double x){
        final int PRECISION = 5;
        double res = x;
        for(int i=1 ; i <= PRECISION; i++){
            if(i % 2 == 0){
                res += pow(x, 2* i+1) /fact(2 * i +1);
            }else{
                res -= pow(x, 2*i+1) /fact(2 * i +1);
            }
        }
        return res;
    }
    public static double cos(double x){
        final int PRECISION = 5;
        double res = 1;
        
        for(int i=1;i<=PRECISION;i++){
            if(i % 2 == 0){
                res += pow(x, 2* i) /fact(2 * i );
            }else{
                res -= pow(x, 2*i) /fact(2 * i);
            }
        }
        return res;
    }
    public static boolean isPrime(int x){
        if(x<=1) return false;
        if(x==2) return true;
        for(int i=2; i<=x/2; i++){
            if(x % i == 0) return false;
        }
        return true;
    }
}

class Program01 {
    public static void main(String[] args) {
        System.out.println(Math.cos(30 * 3.14 / 180));
        System.out.println(Matek.cos(30 * 3.14 / 180));     
        System.out.println(Matek.fact(4));      
    }
}