#include<iostream>
#include<vector>
#include<string>
#include<math.h>
#include<algorithm>
#include<numeric>
#include<list>
#include<stack>

using namespace std;

typedef long long LL;
typedef unsigned long long ULL;
typedef vector<LL> VLL;
typedef vector<ULL> VULL;

typedef signed short Hitoketa;

class MYCP {
public:

	static const LL TEISUU = 1000 * 1000 * 1000 + 7;

	static LL DebugFlag;

	//数値を区切って文字列にする
	static string MakeString_LongLong(vector<long long> const& numbers, string const& str) {
		if (numbers.size() == 0)return "";
		string result = "" + to_string(numbers[0]);
		for (long long i = 1; i < numbers.size(); i++) {
			result += str;
			result += to_string(numbers[i]);
		}

		return result;
	}

	//空白で区切る為のオーバーロード
	static string MakeString_LongLong(vector<long long> const& numbers) {
		if (numbers.size() == 0)return "";
		string result = "" + to_string(numbers[0]);
		for (long long i = 1; i < numbers.size(); i++) {
			result += " ";
			result += to_string(numbers[i]);
		}

		return result;
	}



	//文字列の配列を改行を挟んでまとめる
	static string MakeString_VectorString(vector<string> const& str) {
		string result = "";
		for (long long i = 0; i < str.size(); i++) {
			result += str[i] + "\n";
		}

		return result;
	}

	//文字列を必要な個数だけ読み取る
	static vector<string> MyReadLineSplit(LL n) {
		vector<string> str(n);
		for (long long i = 0; i < n; i++) {
			std::cin >> str[i];
		}

		return str;
	}

	//数値を必要な個数だけ読み取る
	static vector<long long> ReadInts(long long number) {
		vector<long long> a(number);
		for (int i = 0; i < number; i++) {
			std::cin >> a[i];
		}

		return a;
	}

	//渡された自然数が素数ならtureを返す
	static bool PrimeCheck_Int(long long number) {
		if (number < 2)return false;

		for (ULL i = 2; i*i <= number; i++) {
			if (number%i == 0)return false;
		}

		return true;
	}

	//渡された数値以下の素数表を作る
	static vector<long long> MakePrimeList(long long n) {
		vector<long long> list;
		LL i, j, p;
		bool flag;
		for (i = 2; i <= n; i++) {
			flag = true;
			for (j = 0; j < list.size(); j++) {

				if (!(list[j] * list[j] <= i))break;

				if (i%list[j] == 0) {
					flag = false;
					break;
				}
			}
			if (flag)list.push_back(i);
		}

		return list;
	}



	//文字列の分割
	static vector<string> split(string const& str, char sep)
	{
		vector<std::string> v;        // 分割結果を格納するベクター
		auto first = str.begin();              // テキストの最初を指すイテレータ
		while (first != str.end()) {         // テキストが残っている間ループ
			auto last = first;                      // 分割文字列末尾へのイテレータ
			while (last != str.end() && *last != sep)       // 末尾 or セパレータ文字まで進める
				last++;
			v.push_back(string(first, last));       // 分割文字を出力
			if (last != str.end())
				last++;
			first = last;          // 次の処理のためにイテレータを設定
		}
		return v;
	}

	//合計を求める
	static LL Sum(vector<LL> a) {
		LL i, sum = 0;

		for (i = 0; i < a.size(); i++) {
			sum += a[i];
		}

		return sum;
	}

	//小文字ならtrueを返す
	static bool Komoji(char a) {
		if (a >= 'a'&&a <= 'z')return true;

		return false;
	}

	//大文字ならtrueを返す
	static bool Oomoji(char a) {
		if (a >= 'A'&&a <= 'Z')return true;

		return false;
	}

	//切り上げの整数値割り算
	static LL KiriageWarizan(LL a, LL b) {
		LL result = a / b;

		if (a%b > 0)result++;

		return result;
	}

	static LL GreatestCommonFactor(LL a, LL b) {
		LL temp;
		if (a < b) {
			temp = b;
			b = a;
			a = temp;
		}

		while (true)
		{
			temp = a % b;
			a = b;
			b = temp;
			if (b == 0)break;
		}

		return a;
	}

	static LL LeastCommonMultiple(LL a, LL b) {
		return (a / GreatestCommonFactor(a, b))*b;
	}

	static LL DebugPrintf(string output) {

		if (MYCP::DebugFlag != 0) {
			std::cout << output << endl;
		}

		return MYCP::DebugFlag;
	}

	static  LL DebugCin() {
		LL a;

		if (MYCP::DebugFlag != 0) {
			cin >> a;
		}

		return a;
	}
};
LL MYCP::DebugFlag = 0;

//累積和を求めるクラス
class Syakutori {
private:
	vector<LL> list;

public:

	void MakeArray(vector<LL> data) {
		LL i;
		list = data;
		list.push_back(0);
		list[0] = 0;
		for (i = 1; i < list.size(); i++) {
			list[i] = list[i - 1] + data[i - 1];
		}

	}

	LL Sum(LL start, LL end) {
		if (end < start) {
			std::cout << "startがendより大きいです";
			return 0;
		}
		if (start < 0 || end >= list.size()) {
			std::cout << "範囲が異常";
			return 0;
		}

		return list[end] - list[start];
	}

};

class Unlimited_Integer {
private:
	Hitoketa sign;
	vector<Hitoketa> numbers;


	

public:

	Unlimited_Integer(string value) {
		LL i, j, k;

		this->sign = 1;
		k = 0;

		if (value[0] == '-') {
			sign = -1;
			k = 1;
		}

		vector<Hitoketa> temp(value.size() - k, 100);

		this->numbers = temp;

		for (i = value.size() - 1, j = 0; i >= k; i--, j++) {
			this->numbers[j] = (Hitoketa)(value[i] - '0');
		}

	}

	Unlimited_Integer(LL value) {
		Unlimited_Integer temp(to_string(value));
		this->Copy(temp);
	}

	Unlimited_Integer() {
		Unlimited_Integer temp(0);
		this->Copy(temp);
	}

	string To_string() {
		LL i, j, k;

		string result = "";

		if (this->sign == -1) {
			result += "-";
		}

		for (i = this->numbers.size() - 1; i >= 0; i--) {
			result += (char)(this->numbers[i] + '0');
		}

		return result;
	}

	void Copy(Unlimited_Integer a) {
		this->numbers = a.numbers;
		this->sign = a.sign;
	}

	void operator =(Unlimited_Integer const& a) {
		this->Copy(a);
	}

	Unlimited_Integer operator +(Unlimited_Integer const& a) {
		Unlimited_Integer result;

		LL max_keta = max(a.numbers.size(), this->numbers.size()) + 1;

		if (true) {
			VLL temp(max_keta, 0);

			
		}
	}
};

//ここからメイン
int main(void) {
	MYCP::DebugFlag = 0;

	LL i, j, k, n, m;

	LL d, g, min_problem_count;

	cin >> d >> g;

	VLL p(d), c(d);

	VLL sum_point_list(d);

	for (i = 0; i < d; i++) {
		cin >> p[i] >> c[i];

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

	min_problem_count = 0;
	for (i = 0; i < d; i++)min_problem_count += p[i];

	VLL finish_or_not(d, 0);

	while (true)
	{
		finish_or_not[0]++;
		for (i = 0; i < d; i++) {
			if (i + 1 < d) {
				finish_or_not[i + 1] += (finish_or_not[i] / 2);
			}

			finish_or_not[i] %= 2;
		}


		LL problem_count = 0;

		for (i = 0; i < d; i++) {
			if (finish_or_not[i] == 1)problem_count += p[i];
		}

		LL sum_point = 0;

		for (i = 0; i < d; i++) {
			if (finish_or_not[i] == 1) {
				sum_point += sum_point_list[i];
			}
		}

		if (sum_point >= g) {
			if (problem_count < min_problem_count) {
				min_problem_count = problem_count;

				string temp = "更新1:";
				temp += to_string(min_problem_count);
				MYCP::DebugPrintf(temp);
			}
		}

		else
		{

			for (i = 0; i < d; i++) {
				if (finish_or_not[i] == 0) {
					k = sum_point + (i + 1) * 100 * (p[i] - 1);
					if (k >= g) {
						k = g - sum_point;
						k = MYCP::KiriageWarizan(k, (i + 1) * 100);
						k += problem_count;

						if (k < min_problem_count) {
							min_problem_count = k;

							string temp = "更新2:";
							temp += to_string(min_problem_count);
							MYCP::DebugPrintf(temp);
						}
					}
				}
			}
		}


		if (true) {
			LL flag = 0;

			for (i = 0; i < d; i++) {
				flag += finish_or_not[i];
			}

			if (flag == 0) {
				break;
			}
		}
		
	}

	cout << min_problem_count << endl;

	return 0;
}

Measured memory_bytes: 256