include

include <stdio.h>

include <stdlib.h>

using namespace std;

int main()

{

int T;

scanf("%d",&T);

long long n,m,v,k;

while(T--)

{

cin>>n>>m>>v>>k;    int ans=0;    if(n<=m)    {        ans=0;    }else if( m 
    
     m)        {            m= (m-v)*k;            ans++;        }    }    printf("%d\n",ans);}return 0;
    

}