#include <cstdio>
#include <algorithm>

using namespace std;
struct vehicle {
  int x, v;
} a[100001];
bool cmp1(const vehicle & a, const vehicle & b) {
  return a.v > b.v || a.v == b.v && a.x > b.x;
}
bool cmp2(const vehicle & a, const vehicle & b) {
  return a.v < b.v || a.v == b.v && a.x < b.x;
}
int n;
double tl[100001], tr[100001];
double xl[100001], xr[100001];
double vl[100001], vr[100001];
int last;
int ln, rn;
int main() {
  scanf("%d", &n);
  int mini, maxi;
  while (n) {
    mini = maxi = 0;
	for (int i = 0; i < n ; ++i ) {
	  scanf("%d%d", &a[i].x, &a[i].v);
	}
	sort(a, a+n, cmp1);
	tl[0] = 0;
	xl[0] = a[0].x;
	vl[0] = a[0].v;
	last = 0;
	for (int i = 1; i < n ; ++i ) {
	  while (last >= 0 && (a[i].v == vl[last] || a[i].v * tl[last] + a[i].x <= xl[last]))
	    --last;
	  if (last < 0) {
	    last = 0;
		tl[last] = 0;
		xl[last] = a[i].x;
		vl[last] = a[i].v;
	  } else {
	    double tx = a[i].x + tl[last] * a[i].v;
		tl[last+1] = (tx - xl[last]) / (vl[last] - a[i].v) + tl[last]; 
		xl[last+1] = tl[last+1] * a[i].v + a[i].x;
		vl[last+1] = a[i].v;
		++last;
	  }
	}
	ln = last + 1;
	
	tl[ln]=300000;
	sort(a, a+n, cmp2);
	tr[0] = 0;
	xr[0] = a[0].x;
	vr[0] = a[0].v;
	last = 0;
	for (int i = 1; i < n ; ++i ) {
	  while (last >= 0 && (a[i].v == vr[last] || a[i].v * tr[last] + a[i].x >= xr[last]))
	    --last;
	  if (last < 0) {
	    last = 0;
		tr[last] = 0;
		xr[last] = a[i].x;
		vr[last] = a[i].v;
	  } else {
	    double tx = a[i].x + tr[last] * a[i].v;
		tr[last+1] = (tx - xr[last]) / (vr[last] - a[i].v) + tr[last];
		xr[last+1] = tr[last+1] * a[i].v + a[i].x;
		vr[last+1] = a[i].v;
		++last;
	  }
	}
	rn = last + 1;
	tr[rn] = 300000;
	double ans = 300000;
	int j = 0;
	for (int i = 0; i < ln; ++i)
	{
	  while (tr[j] <= tl[i])
	    ++j;
	  --j;
	  if (j < 0) j = 0;
	  if ((tl[i]-tr[j])*vr[j]+xr[j] - xl[i] < ans)
	    ans = (tl[i]-tr[j])*vr[j]+xr[j] - xl[i];
	}
	j = 0;
	for (int i = 0; i < rn; ++i)
	{
	  while (tl[j] <= tr[i])
	    ++j;
	  --j;
	  if (j < 0) j = 0;
	  if (xr[i] - (xl[j]+(tr[i]-tl[j])*vl[j]) < ans)
	    ans = xr[i] - (xl[j]+(tr[i]-tl[j])*vl[j]);
	}
	if (ans < 0) ans = 0;
	printf("%.2lf\n", ans);
	scanf("%d", &n);
  }
}