p,d,m,s=map(int,input().split());
c=0;
while(s>0 and s>=p):
    if(d!=0 and (p<=m or p-d<m)):
        if(p-d<m and p>m):
            s=s-(p-m);
        p=m;
        d=0;
    s=s-p;
    p=p-d;
    c=c+1;
print(c);