#include<bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define maxn 4005
#define put() putchar('\n')
#define Tp template<typename Ty>
#define Ts template<typename Ty,typename... Ar>
using namespace std;
inline void read(int &x){
    int f=1;x=0;char c=getchar();
    while (c<'0'||c>'9') {if (c=='-') f=-1;c=getchar();}
    while (c>='0'&&c<='9') {x=x*10+c-'0';c=getchar();}
    x*=f;
}
namespace Debug{
	Tp void _debug(char* f,Ty t){cerr<<f<<'='<<t<<endl;}
	Ts void _debug(char* f,Ty x,Ar... y){while(*f!=',') cerr<<*f++;cerr<<'='<<x<<",";_debug(f+1,y...);}
	Tp ostream& operator<<(ostream& os,vector<Ty>& V){os<<"[";for(auto& vv:V) os<<vv<<",";os<<"]";return os;}
	#define gdb(...) _debug((char*)#__VA_ARGS__,__VA_ARGS__)
}using namespace Debug;
#define fi first
#define se second
#define mk make_pair
const int mod=1e9+7;
inline int power(int x,int y=mod-2) {
	int sum=1;
	while (y) {
		if (y&1) sum=sum*x%mod;
		x=x*x%mod;y>>=1;
	}
	return sum;
}
int n,a[maxn][maxn],k,N;
double F[16]={0,0,7.987,3.8085,2.396,1.961,1.6065,1.4515,1.2540,1.1980,1.0995,1.0705,1.0345,1.012,1.0015,0.994};
void print(void) {
	int i,j,ans=0;
	// for (i=1;i<=n;i++) for (j=i+2;j<=n;j++) a[i][j]=1;
	for (i=1;i<=n;i++) for (j=i+2;j<=n;j++) ans+=a[i][j];
	printf("%d\n",ans);
	double rating=100*max(0.0,1.0-sqrt(max(0.0,ans*1.0/(n*F[k])-1)));
	gdb(ans,k,rating);
	for (i=1;i<=n;i++) for (j=i+2;j<=n;j++) if (a[i][j]) printf("%d %d\n",i,j);
}
namespace BL2 {
	void solve(int l,int r) {
		if (r-l+1<=2) return ;
		int mid=l+r>>1,i;
		for (i=l;i<mid;i++) a[i][mid]=1;
		for (i=mid+1;i<=r;i++) a[mid][i]=1; 
		solve(l,mid-1);
		solve(mid+1,r);
	}
	void main(void) {
		int i,j;
		solve(1,n);
		print();
	}
}//k=2
const int base=11;
namespace BL3 {
	int id[maxn],tot;
	void solve(int l,int r) {
		if (r-l+1<=2) return ;
		int mid=l+r>>1,i;
		for (i=l;i<mid;i++) a[id[i]][id[mid]]=1;
		for (i=mid+1;i<=r;i++) a[id[mid]][id[i]]=1; 
		solve(l,mid-1);
		solve(mid+1,r);
	}
	void main(int n) {
		int i,j;
		for (i=2;i<n;i*=2) {
			for (j=1;j+i<=n;j+=i) a[j][j+i]=1;
		}
		int t=(k-1)/2,l;
		i=(1<<t);
		for (j=1;j<=n;j+=i) {
			int res=t/2,x=(1<<t/2)+j;
			// for (l=t/2;l<=t;l++) a[x][(1<<l)+j]=1;
			// for (l=0;l<=t/2;l++) a[j+(1<<l)][x]=1;
			for (l=t/2;l<=t;l++) a[(1<<l)+j][(1<<t)+j]=1;
			for (l=0;l<=t/2;l++) a[j][j+(1<<l)]=1;
		}
		for (j=1;j<=n;j+=i) id[++tot]=j;
		solve(1,tot);
		print();
	}
}//k>=11
signed main(void){
	int i;
	read(n);read(k);
	for (i=1;i<=n;i++) a[i][i]=1;
	for (i=1;i<n;i++) a[i][i+1]=1;
	if (k==2) return BL2::main(),0;
	return BL3::main(2048),0;
	return 0;
}
//i=begin && g++ $i.cpp -o $i -std=c++14 && ./$i