// Slower C++ solution:
#include <iostream>

#include <cstdio>

#include <string>

#include <vector>

#include <algorithm>

#include <functional>

#include <iomanip>

#include <stdlib.h>

#include <string.h>

#include <cstring>

#include <cmath>

#include <map>

#include <queue>

#include <deque>

#include <stack>

#include <set>

#include <stdio.h>

#include <tuple>

#include <bitset>

#include <cfloat>

#include <fstream>

#include <limits.h>

#include <list>

#include <math.h>

#include <random>

#include <unordered_map>

#include <unordered_set>

#include <bitset>

#include <numeric>

#include <utility>

#include <sstream>



template<class T> inline bool chmin(T& a, T b) {

	if (a > b) {

		a = b;

		return true;

	}

	return false;

}

template<class T> inline bool chmax(T& a, T b) {

	if (a < b) {

		a = b;

		return true;

	}

	return false;

}



using namespace std;

#define int long long

#define ll long long

#define rep(i, n) for (ll i = 0; i < (n); i++)

#define FOR(i,a,b) for(ll i=(a);i<(b);i++)

#define FORR(i,a,b)for(ll i=(a);i<=(b);i++)

#define repr(i,n) for(ll i=n;i>=0;i--)

#define P pair<ll, ll>

#define sz(x) (ll)x.size()

#define ALL(x) (x).begin(),(x).end()

#define ALLR(x) (x).rbegin(),(x).rend()

#define VE vector<ll>

#define COUT(x) cout<<(x)<<endl

#define MA map<ll,ll>

#define SE set<ll>

#define PQ priority_queue<ll>

#define PQR priority_queue<ll,VE,greater<ll>>

#define COUT(x) cout<<(x)<<endl

#define YES(n) cout << ((n) ? "YES" : "NO"  ) << endl

#define Yes(n) cout << ((n) ? "Yes" : "No"  ) << endl

#define EPS (1e-10)

#define pb push_back



const long long MOD = 1000000007;

//const long long MOD = 998244353;

const long long INF = 1LL << 60;

const double PI = acos(-1.0);





long long modinv(long long a, long long m) {

	long long b = m, u = 1, v = 0;

	while (b) {

		long long t = a / b;

		a -= t * b; swap(a, b);

		u -= t * v; swap(u, v);

	}

	u %= m;

	if (u < 0) u += m;

	return u;

}

ll gcd(ll a, ll b) {

	if (a < b)swap(a, b);

	if (b == 0) return a;

	unsigned r;

	while ((r = a % b)) {

		a = b;

		b = r;

	}

	return b;

}

ll lcm(ll a, ll b) {

	ll g = gcd(a, b);

	return a * b / g;

}

bool prime(ll n) {

	for (ll i = 2; i <= sqrt(n); i++) {

		if (n%i == 0)return false;

	}

	return n != 1;

}

map<ll, ll> prime_factor(ll n) {

	map<ll, ll> ret;

	for (ll i = 2; i * i <= n; i++) {

		while (n % i == 0) {

			ret[i]++;

			n /= i;

		}

	}

	if (n != 1) ret[n] = 1;

	return ret;

}

const int MAX = 2000005;

long long fac[MAX], finv[MAX], inv[MAX];

void COMinit() {

	fac[0] = fac[1] = 1;

	finv[0] = finv[1] = 1;

	inv[1] = 1;

	for (int i = 2; i < MAX; i++) {

		fac[i] = fac[i - 1] * i % MOD;

		inv[i] = MOD - inv[MOD%i] * (MOD / i) % MOD;

		finv[i] = finv[i - 1] * inv[i] % MOD;

	}

}

long long COM(int n, int k) {

	if (n < k) return 0;

	if (n < 0 || k < 0) return 0;

	return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;

}



using Graph = vector<VE>;

vector<pair<char, int>> RunLength(string s) {

	if (s.size() == 0)return {};

	vector<pair<char, int>>res(1, pair<char, int>(s[0], 0));

	for (char p : s) {

		if (res.back().first == p) {

			res.back().second++;

		}

		else {

			res.emplace_back(p, 1);

		}

	}

	return res;

}

const int mod = 1000000007;

struct mint {

	ll x; // typedef long long ll;

	mint(ll x = 0) :x((x%mod + mod) % mod) {}

	mint operator-() const { return mint(-x); }

	mint& operator+=(const mint a) {

		if ((x += a.x) >= mod) x -= mod;

		return *this;

	}

	mint& operator-=(const mint a) {

		if ((x += mod - a.x) >= mod) x -= mod;

		return *this;

	}

	mint& operator*=(const mint a) {

		(x *= a.x) %= mod;

		return *this;

	}

	mint operator+(const mint a) const {

		mint res(*this);

		return res += a;

	}

	mint operator-(const mint a) const {

		mint res(*this);

		return res -= a;

	}

	mint operator*(const mint a) const {

		mint res(*this);

		return res *= a;

	}

	mint pow(ll t) const {

		if (!t) return 1;

		mint a = pow(t >> 1);

		a *= a;

		if (t & 1) a *= *this;

		return a;

	}



	// for prime mod

	mint inv() const {

		return pow(mod - 2);

	}

	mint& operator/=(const mint a) {

		return (*this) *= a.inv();

	}

	mint operator/(const mint a) const {

		mint res(*this);

		return res /= a;

	}

};

struct combination {

	vector<mint> fact, ifact;

	combination(int n) :fact(n + 1), ifact(n + 1) {

		//assert(n < mod);

		fact[0] = 1;

		for (int i = 1; i <= n; ++i) fact[i] = fact[i - 1] * i;

		ifact[n] = fact[n].inv();

		for (int i = n; i >= 1; --i) ifact[i - 1] = ifact[i] * i;

	}

	mint operator()(int n, int k) {

		if (k < 0 || k > n) return 0;

		return fact[n] * ifact[k] * ifact[n - k];

	}

}

comb(20005);

// KETASUU

int GetDigit(int num) {

	return log10(num) + 1;

}



signed main() {

	ios_base::sync_with_stdio(0);

	cin.tie(0);

	cout.tie(0);

	int d, g; cin >> d >> g;

	VE p(d), c(d); rep(i, d)cin >> p[i] >> c[i];

	int ans = INF;

	rep(bit, 1 << d) {

		int now = 0;

		int cnt = 0;

		rep(i, d) {

			if (bit & (1 << i)) {

				now += 100 * (i + 1)*p[i];

				now += c[i];

				cnt += p[i];

			}

		}

		if (now >= g) {

			chmin(ans, cnt); continue;

		}

		for (int i = d - 1; i >= 0; i--) {

			if (!(bit & (1 << i))) {

				rep(j, p[i]) {

					if (j == 0)continue;

					now += (i+1)*100;

					cnt++;

					if (now >= g) {

						chmin(ans, cnt); break;

					}

				}

			}

			if (now >= g) {

				 break;

			}

		}

	}

	cout << ans << endl;

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.7375530122482044x):
#include <iostream>

#include <cstdio>

#include <string>

#include <vector>

#include <algorithm>

#include <functional>

#include <iomanip>

#include <stdlib.h>

#include <string.h>

#include <cstring>

#include <cmath>

#include <map>

#include <queue>

#include <deque>

#include <stack>

#include <set>

#include <stdio.h>

#include <tuple>

#include <bitset>

#include <cfloat>

#include <fstream>

#include <limits.h>

#include <list>

#include <math.h>

#include <random>

#include <unordered_map>

#include <unordered_set>

#include <bitset>

#include <numeric>

#include <utility>

#include <sstream>

#include <cassert>



template<class T> inline bool chmin(T& a, T b) {

	if (a > b) {

		a = b;

		return true;

	}

	return false;

}

template<class T> inline bool chmax(T& a, T b) {

	if (a < b) {

		a = b;

		return true;

	}

	return false;

}



using namespace std;

#define int long long

#define ll long long

#define rep(i, n) for (ll i = 0; i < (n); i++)

#define P pair<ll, ll>

#define sz(x) (ll)x.size()

#define ALL(x) (x).begin(),(x).end()

#define ALLR(x) (x).rbegin(),(x).rend()

#define VE vector<ll>

#define COUT(x) cout<<(x)<<endl

#define MA map<ll,ll>

#define SE set<ll>

#define PQ priority_queue<ll>

#define PQR priority_queue<ll,VE,greater<ll>>

#define COUT(x) cout<<(x)<<endl

#define YES(n) cout << ((n) ? "YES" : "NO"  ) << endl

#define Yes(n) cout << ((n) ? "Yes" : "No"  ) << endl

#define EPS (1e-10)

#define pb push_back



const long long MOD = 1000000007;

//const long long MOD = 998244353;

const long long INF = 1LL << 60;

const double PI = acos(-1.0);

using Graph = vector<VE>;



struct mint {

	ll x; // typedef long long ll;

	mint(ll x = 0) :x((x%MOD + MOD) % MOD) {}

	mint operator-() const { return mint(-x); }

	mint& operator+=(const mint a) {

		if ((x += a.x) >= MOD) x -= MOD;

		return *this;

	}

	mint& operator-=(const mint a) {

		if ((x += MOD - a.x) >= MOD) x -= MOD;

		return *this;

	}

	mint& operator*=(const mint a) {

		(x *= a.x) %= MOD;

		return *this;

	}

	mint operator+(const mint a) const {

		mint res(*this);

		return res += a;

	}

	mint operator-(const mint a) const {

		mint res(*this);

		return res -= a;

	}

	mint operator*(const mint a) const {

		mint res(*this);

		return res *= a;

	}

	mint pow(ll t) const {

		if (!t) return 1;

		mint a = pow(t >> 1);

		a *= a;

		if (t & 1) a *= *this;

		return a;

	}



	// for prime MOD

	mint inv() const {

		return pow(MOD - 2);

	}

	mint& operator/=(const mint a) {

		return (*this) *= a.inv();

	}

	mint operator/(const mint a) const {

		mint res(*this);

		return res /= a;

	}

};

struct combination {

	vector<mint> fact, ifact;

	combination(int n) :fact(n + 1), ifact(n + 1) {

		//assert(n < MOD);

		fact[0] = 1;

		for (int i = 1; i <= n; ++i) fact[i] = fact[i - 1] * i;

		ifact[n] = fact[n].inv();

		for (int i = n; i >= 1; --i) ifact[i - 1] = ifact[i] * i;

	}

	mint operator()(int n, int k) {

		if (k < 0 || k > n) return 0;

		return fact[n] * ifact[k] * ifact[n - k];

	}

}com(10);

struct edge { ll to, cost; };

class UnionFind {

public:

	vector <ll> par; // 各元の親を表す配列

	vector <ll> siz; // 素集合のサイズを表す配列(1 で初期化)



	// Constructor

	UnionFind(ll sz_) : par(sz_), siz(sz_, 1) {

		for (ll i = 0; i < sz_; ++i) par[i] = i; // 初期では親は自分自身

	}

	void init(ll sz_) {

		par.resize(sz_);

		siz.resize(sz_, 1);

		for (ll i = 0; i < sz_; ++i) par[i] = i; // 初期では親は自分自身

	}



	// Member Function

	// Find

	ll root(ll x) { // 根の検索

		while (par[x] != x) {

			x = par[x] = par[par[x]]; // x の親の親を x の親とする

		}

		return x;

	}



	// Union(Unite, Merge)

	bool merge(ll x, ll y) {

		x = root(x);

		y = root(y);

		if (x == y) return false;

		// merge technique（データ構造をマージするテク．小を大にくっつける）

		if (siz[x] < siz[y]) swap(x, y);

		siz[x] += siz[y];

		par[y] = x;

		return true;

	}



	bool issame(ll x, ll y) { // 連結判定

		return root(x) == root(y);

	}



	ll size(ll x) { // 素集合のサイズ

		return siz[root(x)];

	}

};



ll gcd(ll a, ll b) {

	if (a < b)swap(a, b);

	if (b == 0) return a;

	unsigned r;

	while ((r = a % b)) {

		a = b;

		b = r;

	}

	return b;

}

ll lcm(ll a, ll b) {

	ll g = gcd(a, b);

	return a * b / g;

}

bool prime(ll n) {

	for (ll i = 2; i <= sqrt(n); i++) {

		if (n%i == 0)return false;

	}

	return n != 1;

}

map<ll, ll> prime_factor(ll n) {

	map<ll, ll> ret;

	for (ll i = 2; i * i <= n; i++) {

		while (n % i == 0) {

			ret[i]++;

			n /= i;

		}

	}

	if (n != 1) ret[n] = 1;

	return ret;

}

ll modinv(ll a, ll m) {

	ll b = m, u = 1, v = 0;

	while (b) {

		ll t = a / b;

		a -= t * b; swap(a, b);

		u -= t * v; swap(u, v);

	}

	u %= m;

	if (u < 0) u += m;

	return u;

}

vector<pair<char, int>> RunLength(string s) {

	if (s.size() == 0)return {};

	vector<pair<char, int>>res(1, pair<char, int>(s[0], 0));

	for (char p : s) {

		if (res.back().first == p) {

			res.back().second++;

		}

		else {

			res.emplace_back(p, 1);

		}

	}

	return res;

}

// Digit Count

int GetDigit(int num) {

	return log10(num) + 1;

}

// bit calculation[how many "1"] (= __builtin_popcount())

int bit_count(int n) {

	int cnt = 0;

	while (n > 0) {

		if (n % 2 == 1)cnt++;

		n /= 2;

	}

	return cnt;

}

mint POW(mint n, int p) {

	if (p == 0)return 1;

	if (p % 2 == 0) {

		mint t = POW(n, p / 2);

		return t * t;

	}

	return n * POW(n, p - 1);

}

#define ld long double



const int dx[4] = { 1,0,-1,0 };

const int dy[4] = { 0,1,0,-1 };





signed main() {

	ios_base::sync_with_stdio(0);

	cin.tie(0);

	cout.tie(0);

	//cout << fixed << setprecision(15);

	int d, g; cin >> d >> g;

	VE p(d), c(d);

	rep(i, d)cin >> p[i] >> c[i];

	int ans = INF;

	rep(bit, 1 << d) {

		int now = 0;

		int cnt = 0;

		rep(i, d) {

			if (bit &(1 << i)) {

				now += (i + 1) * 100 * p[i] + c[i];

				cnt += p[i];

			}

		}

		if (now >= g) {

			chmin(ans, cnt); continue;

		}

		for (int i = d - 1; i >= 0; i--) {

			if (!(bit & (1 << i))) {

				rep(j, p[i]) {

					if (j == 0)continue;

					now += (i + 1) * 100; cnt++;

					if (now >= g)chmin(ans, cnt);

					if (now >= g)break;

				}

				if (now >= g)break;

			}

		}

	}

	cout << ans << endl;

	return 0;



}