A,B,K=map(int,input().split())
l=[]
for i in range(1,101):
    if A%i==0 and B%i==0:
        l.append(i)
print(l[-K]) A,B,K=map(int,input().split()) A map(int,input().split()) map int input().split() ().split () input split B K l=[] l [] for i in range(1,101):
    if A%i==0 and B%i==0:
        l.append(i) i range(1,101) range 1 101 if A%i==0 and B%i==0:
        l.append(i) A%i==0 and B%i==0 A%i==0 A%i A i 0 B%i==0 B%i B i 0 l.append(i) l.append l append i print(l[-K]) print l[-K] l -K K B,K=map(int,input().split()) map(int,input().split()) B K=map(int,input().split()) map(int,input().split()) K A,B,K=map(int,input().split()) map(int,input().split()) A l=[] [] l
A,B,K=map(int,input().split())
l=[]
for i in range(1,101):
    if A%i==0 and B%i==0:
        l.append(i)
print(l[-K])