A,B,C,D = map(int,input().split())

cnt=0
while D>0:
    if A>0:
        if B>=C:
            A-=1
            B-=C
            if D>=1+C:
                D-=1
                D-=C
                cnt+=1
            else:
                print(cnt)
                exit()
        else:
            print(cnt)
            exit()
    else:
        print(cnt)
        exit()

print(cnt)