from math import ceil
N, M, P, Q = map(int, input().split())
ans, mod = divmod(N, ((12+Q) * M))
if mod <= (P-1)*M:
    print(ans*12+ceil(mod/M))
elif mod >= (P+Q*2)*M:
    print(ans*12+ceil((mod-Q*M)/M))
else:
    mod -= (P-1)*M
    print(ans*12+P-1+ceil(mod/(M*2)))