1 #include <iostream>
2 #include <string>
3 using namespace std;
4
5 int f[33][33];
6 void init(){
7 f[0][0] =1;
8 for(int i=1;i<=31;i++){
9 f[i][0] = f[i-1][0];
10 for(int j=0;j<=i;j++)
11 f[i][j] = f[i-1][j]+f[i-1][j-1];
12 }
13 }
14
15 int change(int x,int b){
16 string s;
17 while(x){
18 s = (char)(x%b+'0')+s;
19 x = x/b;
20 }
21 for(int i=0;i<s.size();i++)
22 if(s[i]>'1'){
23 for(int j=i;j<s.size();j++)
24 s[j] = '1';
25 break;
26 }
27 x =0;
28 for(int i=0;i<s.size();i++){
29 x = x|((s[s.size()-1-i]-'0')<<i);
30 }
31 return x;
32 }
33
34 int cal(int x,int k){
35 int tot =0,ans =0;
36 for(int i=31;i>0;i--){
37 if(x&(1<<i)){
38 tot++;
39 if(tot>k) break;
40 x = x^(1<<i);
41 }
42 if((1<<(i-1))<=x){
43 ans += f[i-1][k-tot];
44 }
45 }
46 if(tot + x==k) ans++;
47 return ans;
48 }
49
50 int main()
51 {
52 init();
53 int x,y;
54 int k,b;
55 cin>>x>>y>>k>>b;
56 x= change(x,b);
57 y = change(y,b);
58 int resx = cal(x-1,k);
59 int resy = cal(y,k);
60 cout<<resy-resx<<endl;
61 return 0;
62 }
