N, M, P, Q = map(int, input().split())

# N 枚の葉っぱ
# 基本 M枚/月
# 2*M枚/月 P, P+1, ... P+Q-1

leaves_to_fall_per_year = M*12 + Q*M

year, nokori = divmod(N, leaves_to_fall_per_year)

for month in range(1, 13):

    if nokori <= 0:
        amari = month - 1
        break

    if P <= month <= P+Q-1:
        leaves_to_fall = 2*M
    else:
        leaves_to_fall = M

    nokori -= leaves_to_fall

else: #break しなかったら
    amari = 12

ans = 12*year + amari
print(ans)