import sys

stdin = sys.stdin

ni = lambda: int(ns())
na = lambda: list(map(int, stdin.readline().split()))
ns = lambda: stdin.readline()

D, G = na()
p = []
c = []
for i in range(D):
    x, y = na()
    p.append(x)
    c.append(y)

# https://qiita.com/_-_-_-_-_/items/34f933adc7be875e61d0
# abcde	s=input()	s='abcde'
# abcde	s=list(input())	s=['a', 'b', 'c', 'd', 'e']
# 5(1つだけ)	a=int(input())	a=5
# 1 2	| x,y = s_inpl()   |	x=1,y=2
# 1 2 3 4 5 ... n 　	li = input().split()	li=['1','2','3',...,'n']
# 1 2 3 4 5 ... n 　	li = inpl()	li=[1,2,3,4,5,...,n]
# FFFTFTTFF 　	li = input().split('T')	li=['FFF', 'F', '', 'FF']

# INPUT
# 3
# hoge
# foo
# bar
# ANSWER
# n=int(input())
# string_list=[input() for i in range(n)]

import math
import copy
from collections import defaultdict, Counter
# 直積 A={a, b, c}, B={d, e}:のとき，A×B={(a,d),(a,e),(b,d),(b,e),(c,d),(c,e)}: product(A, B)
from itertools import product
# 階乗 P!: permutations(seq), 順列 {}_len(seq) P_n: permutations(seq, n)
from itertools import permutations
# 組み合わせ {}_len(seq) C_n: combinations(seq, n)
from itertools import combinations
from bisect import bisect_left, bisect_right
# import numpy as np

def i_inpl(): return int(input())
def s_inpl(): return map(int,input().split())
def l_inpl(): return list(map(int, input().split()))
INF = float("inf")

D, G = s_inpl()
p, c = [], []

for i in range(D):
    pi, ci = s_inpl()
    p.append(pi)
    c.append(ci)

ans = INF
for i in range(1<<D):
    ct = 0
    score = 0
    for j in range(D):
        if i>>j&1:
            score += c[j]
            score += p[j] * (j+1) * 100
            ct += p[j]
    for j in range(D-1, -1, -1):
        if i>>j&1: continue
        if score >= G: break
        g = (j+1)*100
        got = (G-score+g-1)//g
        score += min(got, p[j]) * g
        ct += min(got, p[j])
    ans = min(ans, ct)
print(ans)


### FIXED CODE ###

# https://qiita.com/_-_-_-_-_/items/34f933adc7be875e61d0
# abcde	s=input()	s='abcde'
# abcde	s=list(input())	s=['a', 'b', 'c', 'd', 'e']
# 5(1つだけ)	a=int(input())	a=5
# 1 2	| x,y = s_inpl()   |	x=1,y=2
# 1 2 3 4 5 ... n 　	li = input().split()	li=['1','2','3',...,'n']
# 1 2 3 4 5 ... n 　	li = inpl()	li=[1,2,3,4,5,...,n]
# FFFTFTTFF 　	li = input().split('T')	li=['FFF', 'F', '', 'FF']

# INPUT
# 3
# hoge
# foo
# bar
# ANSWER
# n=int(input())
# string_list=[input() for i in range(n)]

import math
import copy
from collections import defaultdict, Counter
# 直積 A={a, b, c}, B={d, e}:のとき，A×B={(a,d),(a,e),(b,d),(b,e),(c,d),(c,e)}: product(A, B)
from itertools import product
# 階乗 P!: permutations(seq), 順列 {}_len(seq) P_n: permutations(seq, n)
from itertools import permutations
# 組み合わせ {}_len(seq) C_n: combinations(seq, n)
from itertools import combinations
from bisect import bisect_left, bisect_right
# import numpy as np

def i_inpl(): return int(input())
def s_inpl(): return map(int,input().split())
def l_inpl(): return list(map(int, input().split()))
INF = float("inf")

D, G = s_inpl()
p, c = [], []

for i in range(D):
    pi, ci = s_inpl()
    p.append(pi)
    c.append(ci)

ans = INF
for i in range(1<<D):
    ct = 0
    score = 0
    for j in range(D):
        if i>>j&1:
            score += c[j]
            score += p[j] * (j+1) * 100
            ct += p[j]
    for j in range(D-1, -1, -1):
        if i>>j&1: continue
        if score >= G: break
        g = (j+1)*100
        got = (G-score+g-1)//g
        score += min(got, p[j]) * g
        ct += min(got, p[j])
    ans = min(ans, ct)
print(ans)