codeforces round #236 div.2 A

///2014.3.16
///codeforces round #236 div.2
///A

#include <cstdio>
#include <iostream>
using namespace std;

int main()
{
int k,a,b,v;
scanf("%d%d%d%d",&k,&a,&b,&v);
int n = 0;
while( a>0 ){
if( b>=k-1 ){
b -= k-1;
a -= k*v;
n++;
}
else if( b>0 ){
a -= (b+1)*v;
b = 0;
n++;
}
else{
a -= v;
n++;
}
}
printf("%d",n );
return 0;
}