根据题目给出的规则，进行模拟

#include<iostream>
#include<cmath>
using namespace std;

int main(){
    double p, t, g1, g2, g3, gj;
    while(scanf("%lf%lf%lf%lf%lf%lf", &p, &t, &g1, &g2, &g3, &gj)!=EOF){
        if(fabs(g1-g2)<=t){
            printf("%.1lf", (g1+g2)/2);
        }else if(fabs(g3-g1)<=t && fabs(g3-g2)<=t){
            printf("%.1lf", (g1+g2+g3)/2);
        }else if(fabs(g3-g1)>t && fabs(g3-g2)>t){
            printf("%.1lf", gj);
        }else {
            if(fabs(g3-g1) < fabs(g3-g2))
                printf("%.1lf", (g1+g3)/2);
            else printf("%.1lf", (g2+g3)/2);
        }
    }
}