#include <bits/stdc++.h>
using namespace std;
#define fori(n) for (int i = 0; i < (n); i++)
#define forj(n) for (int j = 0; j < (n); j++)
#define FOR(a,b,c) for (int a = (b); a < (c); ++a)
#define forfill(n,x) for (int zzz = 0; zzz < (n); zzz++) cin >> x[zzz]
#define all(x) (x).begin(), (x).end()
#define allr(x) (x).rbegin(), (x).rend()
#define unsync cin.sync_with_stdio(false), cin.tie(0)
#define inoutfile freopen("input.txt", "r", stdin);freopen("output.txt", "w", stdout)
//scanf("%d",&n);
#define INFINITY (1e+300*1e+300)

typedef long long lng;
typedef pair<int, int> pii;
typedef pair<lng, lng> pll;
typedef vector<int> vi;
typedef vector<vector<int>> vii;
typedef vector<pair<int, int>> vpii;
int a, b, c;

struct point {
	long long x, y;
};

point start, endp;


double dist(point a, point b) {
	double x = a.x - b.x;
	double y = a.y - b.y;
	return sqrt(x*x + y*y);
}

int main()
{
	scanf("%d%d%d", &a, &b, &c);
	scanf("%I64d %I64d %I64d %I64d", &(start.x), &(start.y), &(endp.x), &(endp.y));

	point startLineV;
	point startLineX;
	point endLineV;
	point endLineX;

	startLineV.x = start.x;
	startLineX.y = start.y;

	endLineV.x = endp.x;
	endLineX.y = endp.y;


	double startToLineV = INFINITY, startToLineX = INFINITY, endToLineV = INFINITY, endToLineX = INFINITY;

	startLineV.y = -c - a * startLineV.x;
	if (startLineV.y % b == 0) {
		startLineV.y /= b;
		startToLineV = dist(start, startLineV);
	}
	startLineX.x = -c - b * startLineX.y;
	if (startLineX.x % a == 0) {
		startLineX.x /= a;
		startToLineX = dist(start, startLineX);
	}
	endLineV.y = -c - a * endLineV.x;
	if (endLineV.y % b == 0) {
		endLineV.y /= b;
		endToLineV = dist(endp, endLineV);
	}
	endLineX.x = -c - b * endLineX.y;
	if (endLineX.x % a == 0) {
		endLineX.x /= a;
		endToLineX = dist(endp, endLineX);
	}

	double v[] = {
		startToLineV + endToLineV + dist(startLineV, endLineV),
	startToLineX + endToLineV + dist(startLineX, endLineV),
	startToLineV + endToLineX + dist(startLineV, endLineX),
	startToLineX + endToLineX + dist(startLineX, endLineX),
	abs(start.x -endp.x)+abs(start.y-endp.y)
	};

	printf("%.8lf", *min_element(v, v + 5));
	//y=(-c-ax)/b
	//ax+by+c=0.
	//printf("%d\n", stolen)

}