import sys
input = lambda: sys.stdin.readline().rstrip()
ii = lambda: int(input())
mi = lambda: map(int, input().split())
li = lambda: list(mi())
rec = False #再帰を使うときはこれをTrueにする
if rec:
    sys.setrecursionlimit(5 * 10 ** 5)
    from pypyjit import set_param
    set_param('max_unroll_recursion=-1')
inf = 2 ** 63 - 1
mod = 998244353

class Cumsum1d():
    def __init__(self, A):
        self.n = len(A)
        self.Suma = [0] * (self.n + 1)
        for i in range(self.n):
            self.Suma[i + 1] += self.Suma[i] + A[i]

    def query(self, l, r):
        #0-indexed
        return self.Suma[r] - self.Suma[l]

    def get(self, i):
        return self.Suma[i + 1] - self.Suma[i]

    def __getitem__(self, p):
        if isinstance(p, int):
            return self.get(p)
        else:
            return self.query(p.start, p.stop)


a, b, s = mi()

A = [a - i for i in range(a)]
B = [b - i for i in range(b)]
A = [0] + A
B = [0] + B


B = Cumsum1d(B)
ans = 0
for i in range(1, a + 1):
    ans += A[i] * B[0:min(s // i + 1, b + 1)]
print(ans)