#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int maxn=17,INF=0x3f3f3f3f;
int n,m,K,N,x[maxn],y[maxn],g[1<<maxn],f[1<<maxn][maxn];
void Rabit_in(){
	scanf("%d%d%d",&m,&K,&n);int i,v,l,r,s,t;
	for(i=0;i<n;i++)scanf("%d%d",&x[i],&y[i]);
	N=1<<n;
	for(v=1;v<N;v++){
		s=l=m,t=r=0;
		for(i=0;i<n;i++)
			if(v&(1<<i)){
				if(s>x[i])s=x[i];
				if(t<x[i])t=x[i];
				if(l>y[i])l=y[i];
				if(r<y[i])r=y[i];	
			}
		g[v]=t-s+r-l+2;
	}
}
void Rabit_min(int &x,int y){if(x>y)x=y;}
int Rabit_ans(){
	memset(f,0x3f,sizeof(f));
	f[0][0]=0;int v,i,j,ans=INF;
	for(v=1;v<N;v++)
	for(i=v;i;i=(i-1)&v)
	for(j=1;j<=K;j++)
		Rabit_min(f[v][j],f[v^i][j-1]+g[i]);
	for(i=1;i<=K;i++)
		Rabit_min(ans,f[N-1][i]);
	return ans;
}
void Rabit_main(){
	Rabit_in();
	printf("%d\n",Rabit_ans()<<1);
}
int main(){
#define _Rabit _RABIT
#ifdef _Rabit
	freopen("xfence.in","r",stdin);
	freopen("xfence.out","w",stdout);
#endif
	Rabit_main();
#ifndef _Rabit
	getchar(),getchar();
#endif
	fclose(stdin);fclose(stdout);
	return 0;
}