extern crate core;

use std::fmt;
use std::cmp::{Ordering, min, max};
use std::f32::MAX;
use std::ops::{Add, Sub, Mul, Div, Neg, Index, IndexMut, SubAssign};
use std::collections::{BTreeMap, VecDeque, BinaryHeap, BTreeSet};
use std::fmt::{Display, Formatter, Error};

fn show<T: Display>(vec: &Vec<T>) {
    if vec.is_empty() {
        println!("[]");
    }else {
        print!("[{}", vec[0]);
        for i in 1 .. vec.len() {
            print!(", {}", vec[i]);
        }
        println!("]");
    }
}
fn show2<T: Display>(vec: &Vec<Vec<T>>) {
    if vec.is_empty() {
        println!("[]");
    }else {
        for l in vec {
            show(l);
        }
    }
}
macro_rules! read_line{
    () => {{
        let mut line = String::new();
        std::io::stdin().read_line(&mut line).ok();
        line
    }};
    (delimiter: ' ') => {
        read_line!().split_whitespace().map(|x|x.to_string()).collect::<Vec<_>>()
    };
    (delimiter: $p:expr) => {
        read_line!().split($p).map(|x|x.to_string()).collect::<Vec<_>>()
    };
    (' ') => {
        read_line!(delimiter: ' ')
    };
    ($delimiter:expr) => {
        read_line!(delimiter: $delimiter)
    };
    (' '; $ty:ty) => {
        read_line!().split_whitespace().map(|x|x.parse::<$ty>().ok().unwrap()).collect::<Vec<$ty>>()
    };
    ($delimiter:expr; $ty:ty) => {
        read_line!($delimiter).into_iter().map(|x|x.parse::<$ty>().ok().unwrap()).collect::<Vec<$ty>>()
    };
}
macro_rules! read_value{
    () => {
        read_line!().trim().parse().ok().unwrap()
    }
}
macro_rules! let_all {
    ($($n:ident:$t:ty),*) => {
        let line = read_line!(delimiter: ' ');
        let mut iter = line.iter();
        $(let $n:$t = iter.next().unwrap().parse().ok().unwrap();)*
    };
}
macro_rules! let_mut_all {
    ($($n:ident:$t:ty),*) => {
        let line = read_line!(delimiter: ' ');
        let mut iter = line.iter();
        $(let mut $n:$t = iter.next().unwrap().parse().ok().unwrap();)*
    };
}
trait Order {
    type Output;
    fn sorted(&self) -> Self::Output;
}
impl <T: Ord + Clone> Order for Vec<T> {
    type Output = Self;
    fn sorted(&self) -> Self::Output {
        let mut result = self.clone();
        result.sort();
        result
    }
}
trait SortedVec<T> {
    fn lower_bound(&self, target: &T) -> usize;
    fn upper_bound(&self, target: &T) -> usize;
}
impl <T: Ord> SortedVec<T> for Vec<T> {
    fn lower_bound(&self, target: &T) -> usize {
        let mut left = 0;
        let mut right = self.len();
        while left < right {
            let mid = (left + right) / 2 ;
            if self[mid] < *target {
                left = mid + 1;
            }else {
                right = mid;
            }
        }
        right
    }

    fn upper_bound(&self, target: &T) -> usize {
        let mut left = 0;
        let mut right = self.len();
        while left < right {
            let mid = (left + right) / 2;
            if self[mid] <= *target {
                left = mid + 1;
            }else {
                right = mid;
            }
        }
        right
    }
}
fn solve(current: usize, height: usize, heights: &Vec<i32>, memo: &mut Vec<Vec<f64>>) -> f64 {
    if current == heights.len() {
        0_f64
    }else if memo[current][height] >= 0_f64 {
        memo[current][height]
    }else {
        let mut min_value = std::f64::MAX;
        if height as i32 >= heights[current] {
            let left = (height as i32 - heights[current]) as f64;
            for h in 1 .. heights[current] {
                let diff = left + (heights[current] - h) as f64;
                let area = (((heights[current] - h) * (heights[current] - h)) as f64 + (left * left) as f64) / diff / 2_f64;
                let all = area + solve(current + 1, h as usize, heights, memo);
                if min_value > all {
                    min_value = all;
                }
            }
            for h in heights[current] .. 301 {
                let area = (left + (h - heights[current]) as f64) / 2_f64 + solve(current + 1, h as usize, heights, memo);
                if min_value > area {
                    min_value = area;
                }
            }
        }else {
            let left = (heights[current] - height as i32) as f64;
            for h in 1 .. heights[current] {
                let area = (left + (heights[current] - h) as f64) / 2_f64 + solve(current + 1, h as usize, heights, memo);
                if min_value > area {
                    min_value = area;
                }
            }
            for h in heights[current] .. 301 {
                let diff = left + (h - heights[current]) as f64;
                let area = (((h - heights[current]) * (h - heights[current])) as f64 + left * left) / diff / 2_f64;
                let all = area + solve(current + 1, h as usize, heights, memo);
                if min_value > all {
                    min_value = all;
                }
            }
        }
        memo[current][height] = min_value;
        min_value
    }
}
fn main(){
    let n: usize = read_value!();
    let heights = read_line!(' '; i32);
    let mut memo = vec![vec![-1_f64; 301]; n];
    println!("{:.*}", 10, solve(0, 1, &heights, &mut memo));
}


Measured memory_bytes: 5072