import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.InputMismatchException;
import java.util.List;
import java.util.StringTokenizer;

public class Main {

	public static void main(String[] args) throws IOException {
		InputStream inputStream = System.in;
		OutputStream outputStream = System.out;
		InputReader in = new InputReader(inputStream);
		PrintWriter out = new PrintWriter(outputStream);
		TaskX solver = new TaskX();
		solver.solve(1, in, out);
		out.close();
	}

	static int INF = 1 << 30;
	static long LINF = 1L << 55;
	static int MOD = 1000000007;
	static int[] mh4 = { 0, -1, 1, 0 };
	static int[] mw4 = { -1, 0, 0, 1 };
	static int[] mh8 = { -1, -1, -1, 0, 0, 1, 1, 1 };
	static int[] mw8 = { -1, 0, 1, -1, 1, -1, 0, 1 };

	static class TaskX {

		public void solve(int testNumber, InputReader in, PrintWriter out) {

			int d = in.nextInt();
			long g = in.nextLong();


			long[] p = new long[d], c = new long[d];
			for (int i = 0; i < d; i++) {
				p[i] = in.nextLong();
				c[i] = in.nextLong();

			}

			long ans = LINF;
			for (int i = 0; i < (1 << d); i++) {
				int count = 0;
				long sum = 0;
				for (int j = 0; j < d; j++) {
					if (((i >> j) & 1) == 1) {
						sum += c[j];
						count += p[j];
						sum += p[j] * (j+1) *100;
					}
				}

				if (g <= sum) {
					ans = Math.min(ans, count);
					continue;
				}

				List<Long> list = new ArrayList<>();
				for (int j = 0; j < d; j++) {
					if (((i >> j) & 1) == 0) {
						for (int k = 0; k < p[j]; k++) {
							list.add((long)(j+1)*100);
						}
					}
				}

				Collections.sort(list, Comparator.reverseOrder());

				for (int j = 0; j < list.size(); j++) {
					if (sum >= g) {
						ans = Math.min(ans, count);
						break;
					}

					sum += list.get(j);
					count++;
				}
				ans = Math.min(ans, count);

			}

			out.println(ans);

		}
	}

	static class InputReader {
		BufferedReader in;
		StringTokenizer tok;

		public String nextString() {
			while (!tok.hasMoreTokens()) {
				try {
					tok = new StringTokenizer(in.readLine(), " ");
				} catch (IOException e) {
					throw new InputMismatchException();
				}
			}
			return tok.nextToken();
		}

		public int nextInt() {
			return Integer.parseInt(nextString());
		}

		public long nextLong() {
			return Long.parseLong(nextString());
		}

		public double nextDouble() {
			return Double.parseDouble(nextString());
		}

		public int[] nextIntArray(int n) {
			int[] res = new int[n];
			for (int i = 0; i < n; i++) {
				res[i] = nextInt();
			}
			return res;
		}

		public int[] nextIntArrayDec(int n) {
			int[] res = new int[n];
			for (int i = 0; i < n; i++) {
				res[i] = nextInt() - 1;
			}
			return res;
		}

		public long[] nextLongArray(int n) {
			long[] res = new long[n];
			for (int i = 0; i < n; i++) {
				res[i] = nextLong();
			}
			return res;
		}

		public long[] nextLongArrayDec(int n) {
			long[] res = new long[n];
			for (int i = 0; i < n; i++) {
				res[i] = nextLong() - 1;
			}
			return res;
		}

		public InputReader(InputStream inputStream) {
			in = new BufferedReader(new InputStreamReader(inputStream));
			tok = new StringTokenizer("");
		}
	}

}


Measured memory_bytes: 36408