int main() {
int n;
while(scanf("%d", &n) != EOF) {
int l, h;
double min = FLT_MAX;
scanf("%d %d", &l, &h);
Line Old;
for (int i = 1; i <= n; i++) {
int yi, xf, yf;
scanf("%d %d %d", &yi, &xf, &yf);
Point P1, P2;
if (i % 2 != 0) {
P1.x = 0;
P1.y = yi;
P2.x = xf;
P2.y = yf;
if (l - xf < min)
min = l - xf;
} else {
P1.x = l;
P1.y = yi;
P2.x = xf;
P2.y = yf;
if (xf < min)
min = xf;
}
Line N(P1, P2);
if (i != 1) {
double d = linePointDist(N, Old.Pb, true);
if (d < min)
min = d;
}
Old = N;
}
printf("%.2lf\n", min);
}
return 0;
}
//for segment segment intersection, check additionally
//min(x1,x2) <= x <= max(x1,x2)
//min(y1,y2) <= x <= max(y1,y2)
bool segmentsIntersect( point2d A, point2d B, point2d C, point2d E )
{
point2d in = intersect( makeline(A,B), makeline(C,E) );
return linePointDist(A,B,in,true) < eps && linePointDist(C,E,in,true) < eps;
}