import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################
a,b,s = na()
ans = 0
for i  in range(1, min(a, s)+1):
    for j in range(1, min(b, s//i)+1):
        #print(i, j)
        ans += (a-i+1)*(b-j+1)
print(ans)