A,B,S=map(int,input().split())
def make_divisors(n):
    lower_divisors , upper_divisors = [], []
    i = 1
    while i*i <= n:
        if n % i == 0:
            lower_divisors.append(i)
            if i != n // i:
                upper_divisors.append(n//i)
        i += 1
    return lower_divisors + upper_divisors[::-1]
x=0
for j in range(1,S+1):
    T=make_divisors(j)
    for i in range(len(T)):
        a=T[i]
        b=j//T[i]
        c=max(0,A-a+1)*max(0,B-b+1)
        x+=c
print(x)