#include<stdio.h>

int hamSo(int x){
	int i = 0, s = 1;
	while(1){
		if(x < 0){
			printf("Incorrect input!");
			break;
		}
		i++;
		s += (2 * i - 1);
		if(i == x){
			if(x == 1){
				printf("1 + f(1) + = %d", s);
				break;			
			}
			if(x == 2){
				printf("1 + f(1) + f(2) = %d", s);
				break;			
			}
			if(x == 3){
				printf("1 + f(1) + f(2) + f(3) = %d", s);
				break;			
			}
			if(x > 3){
				printf("1 + f(1) + f(2) + ... + f(%d) = %d",x ,s);
				break;
			}			
		}
	}
	return 0;
}
int main(){
	int m;
	do{
		printf("\nEnter positive integer(0 to quit): ");
		scanf("%d", &m);
		if(m == 0){
			break;
		}
		hamSo(m);
	}while(1);
	return 0;
}