#include <bits/stdc++.h>   using namespace std;   long double sq(long double a) { return a * a; }   long double dist(pair<long double, long double> a,                    pair<long double, long double> b) {     return sqrt((long double)(sq(a.second - b.second) + sq(a.first - b.first)));   }   long double mandist(pair<long long, long long> a,                       pair<long long, long long> b) {     return abs(a.second - b.second) + abs(a.first - b.first);   }   long long a, b, c;   pair<long long, long long> p1, p2;   int main() {     scanf(  %lld%lld%lld , &a, &b, &c);     scanf(  %lld%lld%lld%lld , &p1.first, &p1.second, &p2.first, &p2.second);     if (a == 0 || b == 0)       printf( %.20Lf n , mandist(p1, p2));     else {       long double res = mandist(p1, p2);       long double interhoriz1 =           ((long double)(-c - a * p1.first)) / ((long double)b);       long double interhoriz2 =           ((long double)(-c - a * p2.first)) / ((long double)b);       long double intervert1 =           ((long double)(-c - b * p1.second)) / ((long double)a);       long double intervert2 =           ((long double)(-c - b * p2.second)) / ((long double)a);       res = min(res, abs((long double)p1.second - interhoriz1) +                          abs((long double)p2.second - interhoriz2) +                          dist(make_pair((long double)p1.first, interhoriz1),                               make_pair((long double)p2.first, interhoriz2)));       res = min(res, abs((long double)p1.second - interhoriz1) +                          abs((long double)p2.first - intervert2) +                          dist(make_pair((long double)p1.first, interhoriz1),                               make_pair(intervert2, (long double)p2.second)));       res = min(res, abs((long double)p1.first - intervert1) +                          abs((long double)p2.first - intervert2) +                          dist(make_pair(intervert1, (long double)p1.second),                               make_pair(intervert2, (long double)p2.second)));       res = min(res, abs((long double)p1.first - intervert1) +                          abs((long double)p2.second - interhoriz2) +                          dist(make_pair(intervert1, (long double)p1.second),                               make_pair((long double)p2.first, interhoriz2)));       printf( %.20Lf n , res);     }   }   