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Saleh127

CF 1391C

Aug 10th, 2020
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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define ll long long
  4. ll mod(ll a,ll c,ll mm)
  5. {
  6. if(c==0) return 1;
  7. ll x=mod(a,c>>1,mm);
  8. x=(x*x)%mm;
  9. if(c&1)
  10. {
  11. x=(x*a)%mm;
  12. }
  13. return x;
  14. }
  15.  
  16.  
  17. int main()
  18. {
  19. ios_base::sync_with_stdio(0);
  20. cin.tie(0);
  21. cout.tie(0);
  22.  
  23. ll a,c,d=1,i,j,k=1e9+7,l;
  24. cin>>a;
  25. for(i=2; i<=a; i++)
  26. {
  27. d=(d*i)%k;
  28. }
  29. cout<<(d+k-mod(2,a-1,k))%k<<endl;
  30. return 0;
  31. }
  32.  
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