data = __import__("sys").stdin.readlines()
def boucle(res):
	resu = 0
	for j in range(0,len(res)):
		resu += int(res[j])
	#print(resu)
	if (resu > 9):
		boucle(list(str(resu)))
	else:
		print(resu)


n = len(data)
for i in range(0,n-1):
	res = list(data[i].replace("\n",''))
	boucle(res)