pku2992 Divisors

#include<iostream>
#include<vector>
#include<algorithm>
#include<cstdio>
#include<queue>
#include<stack>
#include<string>
#include<map>
#include<set>
#include<cmath>
#include<cassert>
#include<cstring>
#include<iomanip>
using namespace std;

#ifdef _WIN32
#define i64 __int64
#define out64 "%I64d\n"
#define in64 "%I64d"
#else
#define i64 long long
#define out64 "%lld\n"
#define in64 "%lld"
#endif
/************ for topcoder by zz1215 *******************/
#define FOR(i,a,b)      for( int i = (a) ; i <= (b) ; i ++)
#define FFF(i,a)        for( int i = 0 ; i < (a) ; i ++)
#define FFD(i,a,b)      for( int i = (a) ; i >= (b) ; i --)
#define S64(a)          scanf(in64,&a)
#define SS(a)           scanf("%d",&a)
#define LL(a)           ((a)<<1)
#define RR(a)           (((a)<<1)+1)
#define pb              push_back
#define CL(Q)           while(!Q.empty())Q.pop()
#define MM(name,what)   memset(name,what,sizeof(name))
#define read            freopen("in.txt","r",stdin)
#define write           freopen("out.txt","w",stdout)

const int inf = 0x3f3f3f3f;
const i64 inf64 = 0x3f3f3f3f3f3f3f3fLL;
const double oo = 10e9;
const double eps = 10e-9;
const double pi = acos(-1.0);
const int maxn = 500;

// i64 gcd(i64 a,i64 b){return b?gcd(b,a%b):a;}

i64 gcd(i64 _a, i64 _b)
{
    if (!_a || !_b)
    {
        return max(_a, _b);
    }
    i64 _t;
    while ((_t = _a % _b))
    {
        _a = _b;
        _b = _t;
    }
    return _b;
}

i64 ext_gcd (i64 _a, i64 _b, i64 &_x, i64 &_y)
{
    if (!_b)
    {
        _x = 1;
        _y = 0;

        return _a;
    }
    i64 _d = ext_gcd (_b, _a % _b, _x, _y);
    i64 _t = _x;
    _x = _y;
    _y = _t - _a / _b * _y;
    return _d;
}

i64 invmod (i64 _a, i64 _p)
{
    i64 _ans, _y;
    ext_gcd (_a, _p, _ans, _y);
    _ans < 0 ? _ans += _p : 0;
    return _ans;
}

vector<int>p;
vector<int>g[maxn];
int n,k;

bool isp(int x)
{
	for(int i=0;p[i]*p[i]<=x;i++)
	{
		if(x%p[i] == 0)
		{
			return false;
		}
	}
	return true;
}

void init()
{
	p.clear();
	p.pb(2);
	for(int i=3;i<100000;i++)
	{
		if(isp(i))
		{
			p.pb(i);
		}
	}
	for(int i=0;i<maxn;i++)
	{
		g[i].clear();
	}
	int temp;
	for(int i=2;i<maxn;i++)
	{
		temp = i;
		for(int u=0;p[u]*p[u]<=temp;u++)
		{
			while(temp%p[u]==0)
			{
				temp/=p[u];
				g[i].pb(p[u]);
			}
		}
		if(temp>1)
		{
			g[i].pb(temp);
		}
	}
	return ;
}

int s[maxn];
int dp[maxn][maxn];

int main()
{
	init();
	MM(dp,0);
	for(int u=2;u<maxn;u++)
	{
		for(int i=1;i<maxn;i++)
		{
			dp[u][i] = dp[u-1][i];
		}
		for(int i=0;i<g[u].size();i++)
		{
			dp[u][g[u][i]]++;
		}
	}
	while(scanf("%d%d",&n,&k)!=EOF)
	{
		i64 ans=1;
		for(int i=1;i<=n;i++)
		{
			s[i] = dp
[i];
		}
		for(int i=1;i<=n;i++)
		{
			s[i] -= dp[n-k][i];
		}
		for(int i=1;i<=n;i++)
		{
			s[i] -= dp[k][i];
		}
		for(int i=2;i<=n;i++)
		{
			ans *= s[i]+1;
		}
		printf("%lld\n",ans);
	}
    return 0;
}