#[allow(unused_macros)]
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        let mut next = || { iter.next().unwrap() };
        input_inner!{next, $($r)*}
    };
    ($($r:tt)*) => {
        let stdin = std::io::stdin();
        let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
        let mut next = move || -> String{
            bytes
                .by_ref()
                .map(|r|r.unwrap() as char)
                .skip_while(|c|c.is_whitespace())
                .take_while(|c|!c.is_whitespace())
                .collect()
        };
        input_inner!{next, $($r)*}
    };
}
 
#[allow(unused_macros)]
macro_rules! input_inner {
    ($next:expr) => {};
    ($next:expr, ) => {};
 
    ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
    };
}
 
#[allow(unused_macros)]
macro_rules! read_value {
    ($next:expr, ( $($t:tt),* )) => {
        ( $(read_value!($next, $t)),* )
    };
 
    ($next:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    };
 
    ($next:expr, chars) => {
        read_value!($next, String).chars().collect::<Vec<char>>()
    };
 
    ($next:expr, bytes) => {
        read_value!($next, String).into_bytes()
    };
 
    ($next:expr, usize1) => {
        read_value!($next, usize) - 1
    };
 
    ($next:expr, $t:ty) => {
        $next().parse::<$t>().expect("Parse error")
    };
}

use std::cmp::Ordering;

/// Equivalent to std::lowerbound and std::upperbound in c++
pub trait BinarySearch<T> {
    fn lower_bound(&self, &T) -> usize;
    fn upper_bound(&self, &T) -> usize;
}

impl<T: Ord> BinarySearch<T> for [T] {
    fn lower_bound(&self, x: &T) -> usize {
        let mut low = 0;
        let mut high = self.len();

        while low != high {
            let mid = (low + high) / 2;
            match self[mid].cmp(x) {
                Ordering::Less => {
                    low = mid + 1;
                }
                Ordering::Equal | Ordering::Greater => {
                    high = mid;
                }
            }
        }
        low
    }

    fn upper_bound(&self, x: &T) -> usize {
        let mut low = 0;
        let mut high = self.len();

        while low != high {
            let mid = (low + high) / 2;
            match self[mid].cmp(x) {
                Ordering::Less | Ordering::Equal => {
                    low = mid + 1;
                }
                Ordering::Greater => {
                    high = mid;
                }
            }
        }
        low
    }
}






use std::cmp;
use std::cmp::min;
use std::collections::BTreeMap;
use std::process;
use std::cmp::Ord;
#[derive(PartialEq, Eq)]
pub struct point(i64, i64, i64);
impl Ord for point {
    fn cmp(&self, other: &point) -> Ordering {
        self.0.cmp(&other.0)
    }
}

impl PartialOrd for point {
    fn partial_cmp(&self, other: &point) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}
/*
impl PartialEq for point {
    fn eq(&self, other: &point) -> bool {
        self.0 == other.0
    }
}
impl Eq for point {
    fn eq(&self, other: &point) -> bool {
        self.0 == other.0
    }
}*/

fn dfs(s :&Vec<(i64,i64)>, flag:i64, d:i64, t:i64) -> i64{
    let mut res:i64 = 0;
    let mut score:i64 = 0;
    let mut res:i64 = 0;
    for i in 0..d{
        if ((flag>>i)&1)!=0{
            score += ((i+1)*100*s[i as usize].0 + s[i as usize].1);
            res += s[i as usize].0;
        }
    }
    if score>=t{
        return res;
    }
    for i in (0..d).rev(){
        if ((flag>>i)&1)==0{
            if (t-score)>0{
                res += min( (t-score-1)/((i+1)*100)+1, s[i as usize].0);
                score += min( (t-score-1)/((i+1)*100)+1, s[i as usize].0) * ((i+1)*100);
            }   
        }
        if score>=t{
            return res;
        }
    }

    return res;    
}
fn main() {
    input!{
        d: i64,
        g: i64,
        p:[(i64,i64);d]
    }
    let mut res=10000000;
    for i in 0..1<<d{
        let m = dfs(&p,i,d,g);
        res = min(res,m);
    }
    println!("{}", res);
}


Measured memory_bytes: 4352