nth = int(raw_input('enter number nth: '))
oddprimes = [2]
cont = 2
candidat = 3
while (cont <= nth): #start with nth>=2
	verificator = True
	for i in oddprimes:
		if candidat%i == 0:
			verificator = False
			break
	if verificator:
		oddprimes = oddprimes + [candidat]
		cont = cont + 1
	candidat = candidat + 2
print oddprimes[nth-1]