#include <bits/stdc++.h>   using namespace std;   int a[200005];   long double b[200005];   int n;   long double dp1[200005], dp2[200005];   long double check(long double val) {     int i;     for (i = 0; i < n; i++) b[i + 1] = a[i] - val;     dp1[1] = b[1];     long double ans = b[1];     for (i = 2; i <= n; i++) {       dp1[i] = max(dp1[i - 1], (long double)0) + b[i];       ans = max(ans, dp1[i]);     }     for (i = 0; i <= n + 1; i++) b[i + 1] = -b[i + 1];     ans = max(ans, b[1]);     dp2[1] = b[1];     for (i = 2; i <= n; i++) {       dp2[i] = max(dp2[i - 1], (long double)0) + b[i];       ans = max(ans, dp2[i]);     }     return ans;   }   int main() {     scanf( %d , &n);     int i;     for (i = 0; i < n; i++) scanf( %d , &a[i]);     long double lo, hi;     lo = -(1e4);     hi = 1e4;     long double eps = 1e-12;     while (lo < hi - eps) {       long double mid1, mid2;       mid1 = (2 * lo + hi) / 3;       mid2 = (lo + hi * 2) / 3;       long double sol1, sol2;       sol1 = check(mid1);       sol2 = check(mid2);       if (sol1 < sol2 - eps) {         hi = mid2;       } else {         lo = mid1;       }     }     cout << fixed << setprecision(9) << check(lo) << endl;   }   