veg,meat,mul,limit = map(int,input().split())

vegs = []
for i in range(1,veg+1):
    for j in range(1,meat+1):
        if j == i*mul:
            if limit > i+j:
                vegs.append(i)
            elif limit == i+j:
                vegs.append(i)

if len(vegs) > 1:
    print(max(vegs))
else:
    print(0)