#include <cstdio>#include <cstring>#include <iostream>#include <map>#include <set>#include <vector>#include <string>#include <queue>#include <deque>#include <bitset>#include <list>#include <cstdlib>#include <climits>#include <cmath>#include <ctime>#include <algorithm>#include <stack>#include <sstream>#include <numeric>#include <fstream>#include <functional>using namespace std;#define MP make_pair#define PB push_backtypedef long long LL;typedef unsigned long long ULL;typedef vector<int> VI;typedef pair<int,int> pii;const int INF = INT_MAX / 3;const double eps = 1e-8;const LL LINF = 1e17;const double DINF = 1e60;const int maxn = 500;struct Point {    double x,y;    Point(double x = 0,double y = 0): x(x), y(y) {}    bool operator < (const Point &p) const {        if(fabs(p.x - x) < eps) return y < p.y;        return x < p.x;    }};double sq(double x) { return x * x; }int n;double f[maxn][maxn];Point p[maxn];double dist[maxn][maxn];int main() {    while(scanf("%d",&n) != EOF) {        for(int i = 1;i <= n;i++) {            scanf("%lf%lf",&p[i].x,&p[i].y);        }        for(int i = 1;i <= n;i++) {            for(int j = 1;j <= n;j++) {                f[i][j] = DINF;            }        }        sort(p + 1, p + 1 + n);        for(int i = 1;i <= n;i++) {            for(int j = 1;j <= n;j++) if(i != j) {                dist[i][j] = sqrt(sq(p[i].x - p[j].x) + sq(p[i].y - p[j].y));            }        }        double ans = DINF;        f[1][1] = 0;        for(int i = 1;i <= n;i++) {            int m = i == 1 ? 1 : i - 1;            for(int j = 1;j <= m;j++) {                f[i + 1][i] = min(f[i + 1][i], f[i][j] + dist[j][i + 1]);                f[i + 1][j] = min(f[i + 1][j], f[i][j] + dist[i][i + 1]);                if(i == n) {                    ans = min(ans, f[i][j] + dist[j][n]);                }            }        }        printf("%.2f\n",ans);    }    return 0;}