#include <stdio.h>

main() {
	float x, fra, sig, sum;
	int n, i, j;

	printf("cos(x). Intro x y n : ");
	scanf("%f %d", &x, &n);	
	for(i=0,sum=0;i<=  n;i++) {
		for(j=1,fra=1;j<=2*i;j++) {
			fra *= x/j;
		}
		for(j=1,sig=1;j<=i;j++) {
			sig *= -1;
		}
		sum += fra*sig;
	}	
	printf("cos(%f)=%f\n", x, sum);
}