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Jul 23rd, 2019
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  1. #include <bits/stdc++.h>
  2. #pragma GCC optimize(fast-math)
  3. #define int long long
  4.  
  5. using namespace std;
  6. int pow(int a,int b,int c) {
  7. if (b==0 || a==1) return 1;
  8.  
  9. if (b%2==0) {int k=pow(a,b/2,c); return (k*k)%c; }
  10. else { int k=pow(a,b/2,c); return (((k*k)%c)*a)%c; }
  11. }
  12. int inv(int a, int mod) {
  13. return pow(a,mod-2,mod);
  14. }
  15.  
  16. signed main() {
  17. ios_base::sync_with_stdio(0);
  18. cin.tie(0);
  19. cout.tie(0);
  20.  
  21. /* --------- */
  22. int ans=0;
  23. int n,m,l;
  24. cin>>n>>m>>l;
  25. int mod=1000000007;
  26. int cur=1;
  27. for (int i=1;i<=l && i*m<=n;i++) {
  28. for (int j=1;j<=m;j++) {
  29. cur*=n+1-(i-1)*m-j;
  30. cur%=mod;
  31. cur*=inv((i-1)*m+j,mod);
  32. // cout<<cur<<"\n";
  33. cur%=mod;
  34. // cout<<cur<<"\n";
  35. }
  36. ans+=cur;
  37. ans%=mod;
  38. }
  39. cout<<ans;
  40. /* --------- */
  41. return 0;
  42. }
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