# wiliter2 
# Fig. 31.7 
# input:  41 5 30

u,m,n = map(int, input("u m n=? ").split())
# w[z][x]
w = [[0 for x in range(m+1)] for z in range(u+1)]
for z in range(u+1):
  for x in range(m+1):
    w[z][x] = 1
for y in range(1,n+1):
  for x in range(1,m+1):
    for z in range(y,u+1):
      w [z][x] = w[z][x] + w[z-y][x-1]
print("w =", w[u][m])