#[allow(unused_imports)]
use std::cmp::{Ordering};

#[allow(unused_imports)]
use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, VecDeque};

#[allow(unused_imports)]
use std::io::{stdin, stdout, BufWriter, Write};

#[allow(unused_imports)]
use std::iter::FromIterator;

#[allow(unused_macros)]
macro_rules! min {
    ($x: expr) => ($x);
    ($x: expr, $($z: expr),+) => {{
        std::cmp::min($x, min!($($z),*))
    }}
}

#[allow(unused_macros)]
macro_rules! max {
    ($x: expr) => ($x);
    ($x: expr, $($z: expr),+) => {{
        std::cmp::max($x, max!($($z),*))
    }}
}

#[allow(unused_macros)]
macro_rules! get { 
    ([$t: ty]) => { 
        { 
            let mut line = String::new(); 
            stdin().read_line(&mut line).unwrap(); 
            line.split_whitespace().map(|t|t.parse::<$t>().unwrap()).collect::<Vec<_>>()
        }
    };
    ([$t: ty];$n: expr) => {
        (0..$n).map(|_|get!([$t])).collect::<Vec<_>>()
    };
    ($t: ty) => {
        {
            let mut line = String::new();
            stdin().read_line(&mut line).unwrap();
            line.trim().parse::<$t>().unwrap()
        }
    };
    ($($t: ty),*) => {
        { 
            let mut line = String::new();
            stdin().read_line(&mut line).unwrap();
            let mut iter = line.split_whitespace();
            ($(iter.next().unwrap().parse::<$t>().unwrap(),)*)
        }
    };
    ($t: ty; $n: expr) => {
        (0..$n).map(|_|get!($t)).collect::<Vec<_>>()
    };
    ($($t: ty),*; $n: expr) => {
        (0..$n).map(|_|get!($($t),*)).collect::<Vec<_>>()
    };
}

#[allow(unused_macros)]
macro_rules! debug {
    ($($a:expr),*) => {
        #[cfg(debug_assertions)]
        writeln!(&mut std::io::stderr(), concat!("[DEBUG] ", $(stringify!($a), "={:?} "),*), $($a),*).unwrap();
    }
}

const BIG_STACK_SIZE: bool = true;

#[allow(dead_code)]
fn main() {
    use std::thread;
    if BIG_STACK_SIZE {
        thread::Builder::new()
            .stack_size(32 * 1024 * 1024)
            .name("solve".into())
            .spawn(solve)
            .unwrap()
            .join()
            .unwrap();
    } else {
        solve();
    }
}

struct Graph {
    nodes: Vec<Vec<usize>>,
}

impl Graph {
    fn new(n: usize, ab: Vec<(usize, usize)>) -> Self {
        let mut nodes = vec![Vec::new(); n+1];
        for (a, b) in ab {
            nodes[a].push(b);
            nodes[b].push(a);
        }
        Graph{
            nodes: nodes,
        }
    }

    fn dfs(&self, node: usize, parent: usize, depth: usize) -> (usize, usize) { //(node, depth)
        let mut maxd = depth;
        let mut maxn = node;
        for &next in self.nodes[node].iter() {
            if next == parent {
                continue;
            }
            let (nn, nd) = self.dfs(next, node, depth+1);
            if nd > maxd {
                maxd = nd;
                maxn = nn;
            }
        }
        (maxn,maxd)
    }
}

fn solve() {
    let n = get!(usize);
    let ab = get!(usize, usize; n-1);

    let g = Graph::new(n, ab);
    let (node, depth) = g.dfs(1, 1, 0);
    let (_, diameter) = g.dfs(node, node, 0);

    if diameter % 3 == 1 {
        println!("Second");
    } else {
        println!("First");
    }
}


Measured memory_bytes: 39292