A, B, N, M = map(int, input().split())

if A == B:
    exit(print(A))

if A < B:
    A, B = B, A
    N, M = M, N

# A > B と言える
diff = A - B
ans = B # B食は確定で作れる

# A を diff個でx食作れるとき
# diff - N*x >= x が成り立つ
ans += diff//(N + 1)

print(ans)