a,b,k = map(int,input().split())
ans = []
ab = [a,b]
for i in range(1,max(ab)+1):
  if(a%i == 0 and b%i == 0):
    ans.append(i)
    
print(ans[-k]) a,b,k = map(int,input().split()) a map(int,input().split()) map int input().split() ().split () input split b k ans = [] ans [] ab = [a,b] ab [a,b] a b for i in range(1,max(ab)+1):
  if(a%i == 0 and b%i == 0):
    ans.append(i)
     i range(1,max(ab)+1) range 1 max(ab)+1 max(ab) max ab 1 if(a%i == 0 and b%i == 0):
    ans.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 ans.append(i) ans.append ans append i print(ans[-k]) print ans[-k] ans -k k ab = [a,b] [a,b] ab k = map(int,input().split()) map(int,input().split()) k a,b,k = map(int,input().split()) map(int,input().split()) a ans = [] [] ans b,k = map(int,input().split()) map(int,input().split()) b
a,b,k = map(int,input().split())
ans = []
ab = [a,b]
for i in range(1,max(ab)+1):
  if(a%i == 0 and b%i == 0):
    ans.append(i)
    
print(ans[-k])