UVa 10105 - Polynomial coefficients

//\\__ hr1212 __//\\

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef pair<int,int> pii;
typedef map<int,int> mi;

#define si(a) scanf("%lld",&a)
#define sii(a,b) scanf("%lld %lld",&a,&b)
#define siii(a,b,c) scanf("%lld %lld %lld",&a,&b,&c)
#define pi(a) printf("%lld\n",a)
#define nl printf("\n");
#define pb push_back
#define mp make_pair
#define all(c) (c).begin(),(c).end()
#define f(i,a,b) for(i=a;i<b;i++)
#define rf(i,a,b) for(i=a;i>=b;i--)
#define clr(x,a) memset(x,a,sizeof(x))
#define MAX 1000100
#define MOD 1000000007

ll n,m,dp[30][30],fact[20];


int main(){
    ll r,k,i,c=0,x=0,y=0,j,t,l,z,x1=0,y1=0;
    ll ans=0;string p;


    fact[0]=1;
    f(i,1,20){
        fact[i]=i*fact[i-1];
    }
    while(sii(n,k)!=EOF){
        ans=fact[n];
        f(i,0,k){
            si(x);
            ans/=fact[x];
        }
        pi(ans);
    }
    return 0;
}