BZOJ 1430: monkey fight sequence prufer

According to the conclusions prufer sequence:       

An unrooted trees corresponding to only one prufer sequence, a sequence also corresponds to a unique prufer unrooted trees. 

Number of occurrences of a point sequence are prufer $ deg_ {i} $ times.    

$ $ N-number of points spanning complete graph is $ n ^ {(n-2)} $ a.                    

code:

#include <cstdio> 
#include <algorithm>  
#define ll long long 
#define setIO(s) freopen(s".in","r",stdin) 
using namespace std; 
const ll mod=9999991;   
int main() 
{ 
    // setIO("input"); 
    int i,j,n; 
    scanf("%d",&n);      
    ll ans=1;    
    for(i=1;i<=n-2;++i)  ans=1ll*n*ans%mod;     
    for(i=n-1;i>=1;--i)  ans=1ll*i*ans%mod;   
    printf("%lld\n",ans);   
    return 0; 
}