c grains of rice code example

Example: c grains of rice

#include <stdio.h>
#include <stdlib.h>

int main() {
	long a, b = 1, c = 1, i = 0;
	
	do
	{
	printf("Enter number of boxes: ");
	scanf("%d", &a);
	
	}while(a > 30);
	
	a--;
	
	for(i = 0; i < a; i++)
	{
		b = b * 2;
		c = c + b;
	}
	
	printf("The number of grains is: %d\n\n\n", c);
    
	system("pause");
}