#![allow(unused_imports)]
#![allow(non_snake_case, unused)]

use std::cmp::*;
use std::collections::*;
use std::ops::*;

// https://atcoder.jp/contests/hokudai-hitachi2019-1/submissions/10518254

macro_rules! eprint {
    ($($t:tt)*) => {{
        use ::std::io::Write;
        let _ = write!(::std::io::stderr(), $($t)*);
    }};
}
macro_rules! eprintln {
    () => { eprintln!(""); };
    ($($t:tt)*) => {{
        use ::std::io::Write;
        let _ = writeln!(::std::io::stderr(), $($t)*);
    }};
}
macro_rules! dbg {
    ($v:expr) => {{
        let val = $v;
        eprintln!("[{}:{}] {} = {:?}", file!(), line!(), stringify!($v), val);
        val
    }}
}

macro_rules! mat {
    ($($e:expr),*) => { Vec::from(vec![$($e),*]) };
    ($($e:expr,)*) => { Vec::from(vec![$($e),*]) };
    ($e:expr; $d:expr) => { Vec::from(vec![$e; $d]) };
    ($e:expr; $d:expr $(; $ds:expr)+) => { Vec::from(vec![mat![$e $(; $ds)*]; $d]) };
}

macro_rules! ok {
    ($a:ident$([$i:expr])*.$f:ident()$(@$t:ident)*) => {
        $a$([$i])*.$f($($t),*)
    };
    ($a:ident$([$i:expr])*.$f:ident($e:expr$(,$es:expr)*)$(@$t:ident)*) => { {
        let t = $e;
        ok!($a$([$i])*.$f($($es),*)$(@$t)*@t)
    } };
}

pub fn readln() -> String {
    let mut line = String::new();
    ::std::io::stdin().read_line(&mut line).unwrap_or_else(|e| panic!("{}", e));
    line
}

macro_rules! read {
    ($($t:tt),*; $n:expr) => {{
        let stdin = ::std::io::stdin();
        let ret = ::std::io::BufRead::lines(stdin.lock()).take($n).map(|line| {
            let line = line.unwrap();
            let mut it = line.split_whitespace();
            _read!(it; $($t),*)
        }).collect::<Vec<_>>();
        ret
    }};
    ($($t:tt),*) => {{
        let line = readln();
        let mut it = line.split_whitespace();
        _read!(it; $($t),*)
    }};
}

macro_rules! _read {
    ($it:ident; [char]) => {
        _read!($it; String).chars().collect::<Vec<_>>()
    };
    ($it:ident; [u8]) => {
        Vec::from(_read!($it; String).into_bytes())
    };
    ($it:ident; usize1) => {
        $it.next().unwrap_or_else(|| panic!("input mismatch")).parse::<usize>().unwrap_or_else(|e| panic!("{}", e)) - 1
    };
    ($it:ident; [usize1]) => {
        $it.map(|s| s.parse::<usize>().unwrap_or_else(|e| panic!("{}", e)) - 1).collect::<Vec<_>>()
    };
    ($it:ident; [$t:ty]) => {
        $it.map(|s| s.parse::<$t>().unwrap_or_else(|e| panic!("{}", e))).collect::<Vec<_>>()
    };
    ($it:ident; $t:ty) => {
        $it.next().unwrap_or_else(|| panic!("input mismatch")).parse::<$t>().unwrap_or_else(|e| panic!("{}", e))
    };
    ($it:ident; $($t:tt),+) => {
        ($(_read!($it; $t)),*)
    };
}


pub fn main() {
    let _ = ::std::thread::Builder::new().name("run".to_string()).stack_size(32 * 1024 * 1024).spawn(run).unwrap().join();
}

const MOD: usize = 1_000_000_007;
const INF: i64 = std::i64::MAX/2;

fn solve() {
    let n = read!(usize);
    let sc = read!([char],i64;n);
    let mut slist = vec![];
    let mut clist = vec![];
    for (s,c) in sc {
        slist.push(s);
        clist.push(c);
    }

    let mut map: HashMap<(String,String,bool),i64> = HashMap::new();
    let mut q = BinaryHeap::new();
    q.push(Reverse((0,(String::new(),String::new(),false))));
    while let Some(Reverse(cur)) = q.pop() {
        let d = cur.0;
        let e = cur.1;
        let head = e.0.clone();
        let tail = e.1.clone();
        let h = e.0.chars().collect::<Vec<char>>();
        let t = e.1.chars().collect::<Vec<char>>();
        if t.is_empty() {
            for (id,s) in slist.iter().enumerate() {
                let mut flag = true;
                let mut tail = String::new();
                for i in 0..s.len() {
                    if i>=h.len() {
                        break;
                    }
                    if h[i] != s[s.len()-1-i] {
                        flag = false;
                    }
                }
                if !flag {
                    continue;
                }
                for i in 0..s.len() {
                    tail += &s[i].to_string();
                }
                let mut ret = judge(head.clone(),tail.clone());
                if ret.2 {
                    ret = (String::new(),String::new(),true);
                }
                let cost = d + clist[id];
                let mut val = *map.get(&ret).unwrap_or(&INF);
                if val <= cost {
                    continue;
                }
                *map.entry(ret.clone()).or_insert(0) = cost;
                q.push(Reverse((cost,ret.clone())));
            }
        }
        if h.is_empty() {
            for (id,s) in slist.iter().enumerate() {
                let mut flag = true;
                let mut head = String::new();
                for i in 0..s.len() {
                    if i>=t.len() {
                        break;
                    }
                    if t[t.len()-1-i] != s[i] {
                        flag = false;
                    }
                }
                if !flag {
                    continue;
                }
                for i in 0..s.len() {
                    head += &s[i].to_string();
                }
                let mut ret = judge(head.clone(),tail.clone());
                if ret.2 {
                    ret = (String::new(),String::new(),true);
                }
                let cost = d + clist[id];
                let mut val = *map.get(&ret).unwrap_or(&INF);
                if val <= cost {
                    continue;
                }
                *map.entry(ret.clone()).or_insert(0) = cost;
                q.push(Reverse((cost,ret.clone())));
            }
        }
    }
    let ans = *map.get(&(String::new(),String::new(),true)).unwrap_or(&-1);
    println!("{}",ans);
}

fn judge(head: String, tail: String) -> (String,String,bool) {
    let s = head.clone() + &tail;
    let c = s.chars().collect::<Vec<char>>();
    let n = c.len();
    let mut flag = true;
    for i in 0..n {
        if c[i]!=c[n-1-i] {
            flag = false;
        }
    }
    let h = head.chars().collect::<Vec<char>>();
    let t = tail.chars().collect::<Vec<char>>();
    if h.len() > t.len() {
        let mut tmp = String::new();
        for i in t.len()..h.len() {
            tmp += &h[i].to_string();
        }
        return (tmp,String::new(),flag);
    }
    else {
        let mut tmp = String::new();
        for i in h.len()..t.len() {
            tmp += &t[i-head.len()].to_string();
        }
        return (String::new(),tmp,flag);
    }
}

fn run() {
    solve();
}


Measured memory_bytes: 2480