#include <iostream>
#include <cmath>
using namespace std;
 
double myAtan(double x, int n) {
	double a = x;
	double sum = a;
	double b = a;
	double E = 1 / n;
	for(int i = 1; a > E; i++){
		b *= - x * x;
		a *= b / (2 * i + 1);
		sum += a;
	}
	return sum;
}
 
int main() {
	double x;
	int n;
	cin >> x >> n;
	cout << "my arctg: " << myAtan(x, n) << endl;
    cout << "arctg: " << atan(x) << endl;
    cout << "|arctg - my arctg| = " << abs(myAtan(x, n) - atan(x)) << endl;
	return 0;
}

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