a, b, k = map(int, input().split())
ans = []
for i in range(1, 101):
    if a % i == 0 and b % i == 0:
        ans.append(i)
ans.sort(reverse = True)
print(ans[k-1]) a, b, k = map(int, input().split()) a map(int, input().split()) map int input().split() ().split () input split b k ans = [] ans [] for i in range(1, 101):
    if a % i == 0 and b % i == 0:
        ans.append(i) i range(1, 101) range 1 101 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 ans.sort(reverse = True) ans.sort ans sort reverse = True reverse True print(ans[k-1]) print ans[k-1] ans k-1 k 1 b, k = map(int, input().split()) map(int, input().split()) b k = map(int, input().split()) map(int, input().split()) k ans = [] [] ans a, b, k = map(int, input().split()) map(int, input().split()) a
a, b, k = map(int, input().split())
ans = []
for i in range(1, 101):
    if a % i == 0 and b % i == 0:
        ans.append(i)
ans.sort(reverse = True)
print(ans[k-1])