N,D,K=map(int,input().split())
D_b=[1]
for i in range(D-1):
    D_b.append(D_b[-1]*2)
S=0
for i in range(K):
    S=0
    for j in range(-1,-1*(D+1),-1):
        S=S+D_b[j]
    D_b.append(S)
print(D_b[K])