//Name: Gem Nikki S. Carpio
//Problem 1 : Program accepts values that are not hex (ie, E-Z, symbols)
//Fix: Escape the while loop using a flag variable for values not 0-9, a-z or A-Z
//Problem 2: Starting at the second input, the decimal value is wrong
//Fix: Reset the total

#include <stdio.h>
#include <stdlib.h>
int main(){

	int value;
        int flag = 0;
	char character;
	int total = 0;
while (1)
{
	character = getchar();

	while(character != '\n'){
		if((character >= 'A') && (character <= 'F'))
			value = character - 'A' + 10;
		if((character >= 'a') && (character <= 'f'))
			value = character - 'a' + 10;
		if((character >= '0') && (character <= '9'))
			value = character - '0';
		if(((character > '9') && (character < 'A'))||((character > 'F') && (character < 'a'))||character > 'f')
   		        {flag=1;
                         break;} //turns on flag for inputs not hex             
		total = total * 16 + value;
		character = getchar();
	}	
	
	if (flag!=1)          
	printf("%d\n", total);   //it only prints if input is valid
	else
	{printf("Invalid input");
        break;};
	
	total = 0;               //reset the total for next input
	
}
    system("pause");
	return 0;
}