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

Q=P+Q-1
x=Q-P+1

y=M*((x*2)+(12-x))

ANS=N//y*12
N%=y

for i in range(1,13):
    if N<=0:
        break
    ANS+=1
    if P<=i<=Q:
        N-=2*M
    else:
        N-=M

print(ANS)