#include <stdio.h>
#include <math.h>
long sum(int g,int n);
long sum(int g,int n)
{
	long ketqua=0,k;
	int i,m;
	for (i = 2; i<=n+1; i++)
	{
		m = i - 1;
		k = pow(-1, i) * pow(g, m);
		ketqua = ketqua + k;
	}
	return ketqua;
}
int main()
{
	int x,n;
	long tong;
	printf("Input x:");
	scanf_s("%d", &x);
	printf("Input n:");
	scanf_s("%d", &n);
	tong = sum(x,n);
	printf("S(x,n)=%ld", tong);
	return 1;
}