10
-405 -230 252 -393 -390 -259 97 163 81 -129
 3
10000 -10000 10000
 1
-10000
 20
-16 -23 29 44 -40 -50 -41 34 -38 30 -12 28 -44 -49 15 50 -28 38 -2 0

702.333333333333712
 10000.000000000016371
 0.000000000000000
 113.875000000000043

#include <bits/stdc++.h>
using namespace std;
int i, j, k, l, n, a[200010];
double t, q, p, o, s[200010];
double ab(double x) {
  if (x < 0) x = -x;
  return x;
}
double cal(double p) {
  int i;
  s[0] = 0;
  for (i = 1; i <= n; i++) s[i] = s[i - 1] + a[i] - p;
  double mi = 0, ma = 0, ansx = -10000000, ansn = 1000000;
  for (i = 1; i <= n; i++) {
    if (s[i] < mi) mi = s[i];
    if (s[i] > ma) ma = s[i];
    if (s[i] - mi > ansx) ansx = s[i] - mi;
    if (s[i] - ma < ansn) ansn = s[i] - ma;
  }
  if (ansx < 0) ansx = -ansx;
  if (ansn < 0) ansn = -ansn;
  if (ansn > ansx) ansx = ansn;
  return (ansx);
}
int main() {
  n = 200000;
  for (i = 1; i <= n; i++) a[i] = 0;
  double l = -10000, r = 10000, tl, tr, tm, tm2, m, m2;
  tl = cal(l);
  tr = cal(r);
  while (1) {
    m = (r + l) / 2.0;
    tm = cal(m);
    if (ab(tr - tl) < 0.000001) break;
    m2 = (r + m) / 2.0;
    tm2 = cal(m2);
    if (tm > tm2) {
      l = m;
      tl = tm;
    } else {
      r = m2;
      tr = tm2;
    }
  }
  printf("%.9f\n", tm);
  return 0;
}
