比赛看不懂
之后不确定题意去瞄了题解，需要分类讨论？囧
之后按照队友已经ac的题意
就是求外面一圈周长，直接可以求得

#include<bits/stdc++.h>

using namespace std;

#define sz(X) ((int)X.size())

typedef long long ll;

const int INF = 0x3f3f3f3f;

const int N = 3e5+5;

const double pi = acos(-1.0);

const double eps = 1e-6;

int w;

int a,b,c,d,e;

double B,C1,C2,A1,A2,D;

int sgn(double x) {

    if(fabs(x) < eps) return 0;

    else if(x < 0) return -1;

    else return 1;

}

double solve(double an) {

    if(sgn(an - 2*pi) == 0) return 0;

    else {

        an /= 2;

        double ans = 0;

        ans += 2*w / tan(an);

        return ans;

    }

}

int main(){

    while(~scanf("%d",&w)) {

        double ans = 0;

        scanf("%d %d %d %d %d",&a,&b,&c,&d,&e);

        ans = a+b+c+d;

    //  printf("%.3f\n",ans);

        B = acos( (a*a+b*b-e*e)*1.0 / (2*a*b) );

        C1 = acos( (b*b+e*e-a*a)*1.0 / (2*b*e) );

        A1 = acos( (a*a+e*e-b*b)*1.0 / (2*a*e) );

        D = acos( (c*c+d*d-e*e)*1.0 / (2*c*d) );

        C2 = acos( (c*c+e*e-d*d)*1.0 / (2*c*e) );

        A2 = acos( (e*e+d*d-c*c)*1.0 / (2*e*d) );

        ans += solve(B) + solve(C1+C2) + solve(A1+A2) + solve(D);

        printf("%.3f\n",ans);

    }

    return 0;

}