#include <stdio.h>
int fung(int x, int y){
	int i;
	int sum=1;
	int c=1;
		for(i=1;i<=y;i++){
			c=c*x;
			sum=sum+c;
		}
		return sum;
}

int main(void){
	int a,b;
	a=2;
	b=3;
	printf("%d", fung(a,b));
	return 0;
}