#include <bits/stdc++.h>
#define mod 1000000007
using namespace std;
/*hello stalker
Any data or information stolen is copyright infringement. You  will be reported.*/
long long int i,j,k,t,q,n,m,xm,ym,ii,jj,iii,jjj,row,col,fcost,nn,mm,co,fl;
string s,s1,s2,s3;
char c,c1;
long long int fco,eo,oo,panga,cou,oj,ojv;
map <long long,vector<pair<long long,long long>>> map1,map2,map3;
map<long long,long long>mapp,mapp1[200005];
long long int y[200008],z[262149],yf[200007],zf[3000005],a[100002],x[100005][3],depth[200008];
set <long long> set1,set2;
vector<long long>  v[200009],vz,vv;
vector<tuple<long long,long long,long long>> v1,v2,v3;
double floa,flo;
long long check[200008];
long long maxl(long long x,long long co)
{check[x]=1;
    if(v[x].size()==1 && x!=0)
    {depth[x]=1;
        return 1;
    }

    for(long long i=0;i<v[x].size();i++)
    {
        if(check[v[x][i]]==0 && v[x][i]>x )
       {
             co=max(co,maxl(v[x][i],0));
       }
    }

         depth[x]=1+co;
    return 1+co;
}
long long dfs(long long x,long long i)
{
    check[x]=1;
    if(x!=0 && v[x].size()==1)
    {
        return y[x];
    }

    for(long long oj=0;oj<v[x].size();oj++)
    {
        if(check[v[x][oj]]==0)
        {
            if(i>mapp[depth[v[x][oj]]]+3)
        {check[v[x][oj]]==1;
            y[x]=y[x]^mapp1[v[x][oj]][(i)%mapp[depth[v[x][oj]]]];
        }
           else
            {
                y[x]=y[x]^dfs(v[x][oj],i);mapp1[x][i]=y[x];

           }

        }
    }

    return y[x];

}
int main()
{ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
cin>>n>>m>>ii>>co;
fco=0;
while(fco<co)
{fco=fco+n;
    if(n-m>ii)
    {
        n=n-m;
    }
    else
    {
        n=ii;
    }
    if(fco<=co)
    {
        fl++;
    }
}
cout<<fl;
return 0;
}