#include <cmath>#include <cstdio>#include <string.h>#include<algorithm>using namespace std;const int maxn = 100;const double eps = 1e-8;inline double min(double a,double b){ return a<b?a:b;}inline double sgn(double x) {return fabs(x)<eps?0:(x>0?1:-1);}struct Point{ double x,y; Point(double tx=0,double ty=0){x=tx;y=ty;} bool operator == (const Point& t) const { return sgn(x-t.x)==0 && sgn(y-t.y)==0; }}p[maxn],Set[maxn],st[maxn],tmp[maxn],pp[maxn];struct Seg{Point s,e;};inline double dist(Point a,Point b){return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));}inline double cross(Point a,Point b,Point c){return (b.x-a.x)*(c.y-a.y)-(b.y-a.y)*(c.x-a.x);}inline bool outside(Seg seg,Point p){ return cross(seg.s,seg.e,p)>eps;}inline bool inside(Seg seg,Point p){ return cross(seg.s,seg.e,p)<-eps;}Point Intersect(Point p1, Point p2, Point p3, Point p4, Point& p) { double a1, b1, c1, a2, b2, c2, d; a1 = p1.y - p2.y; b1 = p2.x - p1.x; c1 = p1.x*p2.y - p2.x*p1.y; a2 = p3.y - p4.y; b2 = p4.x - p3.x; c2 = p3.x*p4.y - p4.x*p3.y; d = a1*b2 - a2*b1; if ( fabs(d) < eps ) return false; p.x = (-c1*b2 + c2*b1) / d; p.y = (-a1*c2 + a2*c1) / d; return p;}double W,H;int a[10],n,pn;double CUT(Seg seg,Point p[]){ int i,j,tot=0; Point A,B; A=B=Point(0,0); bool s,e; for(i=0;i<pn;i++){ if(!outside(seg,p[i])) pp[tot++]=p[i]; else { if(i==0&&!outside(seg,p[pn-1])){B=A; pp[tot++]=Intersect(seg.s,seg.e,p[i],p[pn-1],A); } if(i!=0&&!outside(seg,p[i-1])) {B=A; pp[tot++]=Intersect(seg.s,seg.e,p[i],p[i-1],A); } if(!outside(seg,p[i+1])) { B=A; pp[tot++]=Intersect(seg.s,seg.e,p[i],p[i+1],A); } } } pp[tot]=pp[0];pn=tot; memcpy(st,pp,sizeof(pp)); return dist(A,B);}int main(){ int i; while(scanf("%lf%lf",&W,&H)!=EOF){ double ans=1e20; st[4]=st[0]=Point(0,0); st[1]=Point(0,H); st[2]=Point(W,H); st[3]=Point(W,0); memcpy(tmp,st,sizeof(st)); scanf("%d",&n);Seg ts[100]; for(i=0;i<n;i++) { scanf("%lf%lf",&p[i].x,&p[i].y); a[i]=i; }p[n]=p[0]; for(i=0;i<n;i++) ts[i].s=p[i],ts[i].e=p[i+1]; do{ double tlen=0; memcpy(st,tmp,sizeof(tmp)); pn=4; for(i=0;i<n;i++){ tlen+=CUT(ts[a[i]],st); } ans=min(ans,tlen); }while(next_permutation(a,a+n)); printf("Minimum total length = %.3lfn",ans); } return 0;}
