nCr_find.cpp

/*
    maneesh(maik)
*/

#include<iostream>
#include<algorithm>
#include<string>
#include<bitset>
#include<deque>
#include<iterator>
#include<list>
#include<map>
#include<queue>
#include<set>
#include<stack>
#include<unordered_map>
#include<unordered_set>
#include<vector>
using namespace std;
#define ll long long int
#define pb push_back
#define pf push_front
#define fastio ios_base::sync_with_stdio(false);


ll md=1e9+7;
ll fact[1000002],inv[1000002];
ll modex(ll a,ll p)
{
	if(p==0)
		return 1;
	else if(p%2==1)
	{
		return (a*modex(a,p-1))%md;
	}
	else
	{
		ll y=modex(a,p/2)%md;
		return (y*y)%md;
	}
}
void calculate()
{
	ll i,j,k;
	fact[0]=1;
	fact[1]=1;
	for(i=2;i<=1000000;i++)
	{
		fact[i]=(fact[i-1]*i)%md;
	}
	for(i=0;i<=1000000;i++)
	{
		inv[i]=modex(fact[i],md-2);
	}
}
ll ncr(ll n,ll r)
{
	return (((fact[n]*inv[r])%md)*inv[n-r])%md;
}
int main()
{
 calculate();
 cout<<ncr(6,3);

	return 0;
}