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import java.io.IOException;
import java.io.InputStream;
import java.math.BigInteger;
import java.util.*;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

import static java.lang.Math.max;
import static java.lang.Math.min;
import static java.lang.Math.pow;
import static java.lang.Math.abs;

import static java.lang.String.format;


public class Main {
    final static int INF = Integer.MAX_VALUE >> 1;
    final static int MOD = 1_000_000_007;
    final static int[] dx4 = {0, -1, 1, 0};
    final static int[] dy4 = {-1, 0, 0, 1};
    final static int[] dx8 = {-1, -1, -1, 0, 0, 1, 1, 1};
    final static int[] dy8 = {-1, 0, 1, -1, 1, -1, 0, 1};

    public static void main(String[] args) {
        Scanner sc = new Scanner();
        int d = sc.nextInt();
        int g = sc.nextInt();
        int[] p = new int[d], c = new int[d];
        for (int i = 0; i < d; i++) {
            p[i] = sc.nextInt();
            c[i] = sc.nextInt();
        }
        int ans = Integer.MAX_VALUE;
        for (int comp = 0; comp <= (1 << d) - 1; comp++) {
            //putE(format("completeBit:%s", Integer.toString(comp, 2)));
            int val = 0;
            int proNum = 0;
            for (int i = 0; i < d; i++) {
                int flag = (comp>>i) & 1;
                if (flag == 0) continue;
                int score=100 * (i + 1);
                val += p[i] *score + c[i];
                proNum += p[i];
            }
            //putE(format("val_TMP:%d,proNum;%d", val, proNum));
            for (int i = d - 1; i >= 0&&val<g; i--) {
                int flag = (comp>>i) & 1;
                if (flag == 1) continue;
                int score=100 * (i + 1);
                if(val+p[i]*score<g){
                    val+=p[i]*score;
                    proNum+=p[i];
                }else{
                    if((g-val)%score==0){
                        //putE(format("g,val,score=%d,%d,%d",g,val,score));
                        proNum+=(g-val)/score;
                        val=g;
                    }else{
                        proNum+=((g-val)/score+1);
                        val+=((g-val)/score+1)*score;
                    }
                    break;
                }
            }
            //putE(format("val_last:%d,proNum:%d",val,proNum));
            if(val<g)continue;
            ans=min(ans,proNum);
        }
        put(ans);


    }


    public static void print(Object object) {
        System.out.print(object);
    }

    public static void put(Object object) {
        System.out.println(object);
    }

    public static void put() {
        System.out.println();
    }

    public static void printE(Object object) {
        System.err.print("DEBUG:" + object);
    }

    public static void putE(Object object) {
        System.err.println("DEBUG:" + object);
    }

    public static void putE() {
        System.err.println("DEBUG:");
    }

    final static private class Scanner {
        private final InputStream in = System.in;
        private final byte[] buffer = new byte[1024];
        private int ptr = 0;
        private int buflen = 0;

        private boolean hasNextByte() {
            if (ptr < buflen) {
                return true;
            } else {
                ptr = 0;
                try {
                    buflen = in.read(buffer);
                } catch (IOException e) {
                    e.printStackTrace();
                }
                if (buflen <= 0) {
                    return false;
                }
            }
            return true;
        }

        private int readByte() {
            if (hasNextByte())
                return buffer[ptr++];
            else
                return -1;
        }

        private boolean isPrintableChar(int c) {
            return 33 <= c && c <= 126;
        }

        public boolean hasNext() {
            while (hasNextByte() && !isPrintableChar(buffer[ptr]))
                ptr++;
            return hasNextByte();
        }

        public String next() {
            if (!hasNext())
                throw new NoSuchElementException();
            StringBuilder sb = new StringBuilder();
            int b = readByte();
            while (isPrintableChar(b)) {
                sb.appendCodePoint(b);
                b = readByte();
            }
            return sb.toString();
        }

        public long nextLong() {
            if (!hasNext())
                throw new NoSuchElementException();
            long n = 0;
            boolean minus = false;
            int b = readByte();
            if (b == '-') {
                minus = true;
                b = readByte();
            }
            if (b < '0' || '9' < b) {
                throw new NumberFormatException();
            }
            while (true) {
                if ('0' <= b && b <= '9') {
                    n *= 10;
                    n += b - '0';
                } else if (b == -1 || !isPrintableChar(b)) {
                    return minus ? -n : n;
                } else {
                    throw new NumberFormatException();
                }
                b = readByte();
            }
        }

        public int nextInt() {
            long nl = nextLong();
            if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
                throw new NumberFormatException();
            return (int) nl;
        }

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

    final static private class FixedLongPair {
        final public long x, y;
        final static public FixedLongPair ZEROS = new FixedLongPair(0, 0);

        FixedLongPair(long x, long y) {
            this.x = x;
            this.y = y;
        }

        public static double distance(FixedLongPair flp1, FixedLongPair flp2) {
            double x = (double) flp1.x - flp2.x;
            double y = (double) flp1.y - flp2.y;
            return Math.sqrt(x * x + y * y);
        }

        @Override
        public int hashCode() {
            return (int) x + (int) y;
        }

        @Override
        public boolean equals(Object obj) {
            boolean result = super.equals(obj);
            if (obj.getClass() != this.getClass()) {
                return false;
            }
            FixedLongPair pair = (FixedLongPair) obj;
            if (this.x == pair.x && this.y == pair.y) return true;
            return false;
        }

        @Override
        public String toString() {
            return String.format(FixedLongPair.class.getSimpleName() + ":(%d,%d)", x, y);
        }
    }

    final static private class FixedIntPair {
        final public int x, y;
        final static public FixedIntPair ZEROS = new FixedIntPair(0, 0);

        FixedIntPair(int x, int y) {
            this.x = x;
            this.y = y;
        }

        public static double distance(FixedIntPair fip1, FixedIntPair fip2) {
            double x = (double) fip1.x - fip2.x;
            double y = (double) fip1.y - fip2.y;
            return Math.sqrt(x * x + y * y);
        }

        @Override
        public int hashCode() {
            return x + y;
        }

        @Override
        public boolean equals(Object obj) {
            boolean result = super.equals(obj);
            if (obj.getClass() != this.getClass()) {
                return false;
            }
            FixedIntPair pair = (FixedIntPair) obj;
            if (this.x == pair.x && this.y == pair.y) return true;
            return false;
        }

        @Override
        public String toString() {
            return String.format(FixedIntPair.class.getSimpleName() + ":(%d,%d)", x, y);
        }
    }

    final static private class Tuple<T, V> {
        //immutabl1でないことに注意(T,Vがmutableの場合変更可能)
        final private T t;
        final private V v;

        Tuple(T t, V v) {
            this.t = t;
            this.v = v;
        }

        public T getT() {
            return t;
        }

        public V getV() {
            return v;
        }

        @Override
        public int hashCode() {
            return (t.hashCode() + v.hashCode());
        }

        @Override
        @SuppressWarnings("unchecked")
        public boolean equals(Object obj) {
            if (obj.getClass() != this.getClass()) {
                return false;
            }
            Tuple<T, V> tuple = (Tuple<T, V>) obj;
            return tuple.t.equals(this.t) && tuple.v.equals(this.v);
        }

        @Override
        public String toString() {
            return String.format("<Tuple>=<%s,%s>", t, v);
        }
    }

    final static private class Util {
        static long gcd(long a, long b) {
            //最大公約数　
            if (a % b == 0) return b;
            return gcd(b, a % b);
        }

        static long lcm(long a, long b) {
            //最小公倍数
            long gcd = gcd(a, b);
            long result = b / gcd;
            return a * result;
        }

        static <T extends Comparable<T>> Map<T, Integer> count(List<T> list) {
            //副作用
            Collections.sort(list);
            Map<T, Integer> result = new HashMap<>();
            int l = 0, r = 0;
            while (l < list.size()) {
                while (r < list.size() - 1 && list.get(r).equals(r + 1)) {
                    r++;
                }
                result.put(list.get(r), r - l + 1);
                r++;
                l = r;
            }
            return result;

        }

        static Map<Integer, Integer> count(int[] array) {
            //副作用
            Arrays.sort(array);
            Map<Integer, Integer> result = new HashMap<>();
            int l = 0, r = 0;
            while (l < array.length) {
                while (r < array.length - 1 && array[r] == array[r + 1]) {
                    r++;
                }
                result.put(array[l], r - l + 1);
                r++;
                l = r;
            }
            return result;
        }

        static <T> String toStringBWS(Iterable<T> iterable) {
            Iterator<T> ite = iterable.iterator();
            return toStringBWS(ite);
        }

        static <T> String toStringBWS(Iterator<T> ite) {
            StringBuilder sb = new StringBuilder();
            sb.append(ite.next());
            while (ite.hasNext()) {
                sb.append(" ");
                sb.append(ite.next());
            }
            return sb.toString();
        }

        static int[] factoringInPrimeNumbers(long n, int size) {
            //素因数分解
            //sizeがnに比べて小さい場合完全に素因数分解出来ていない可能性がある
            int[] result = new int[size];
            for (int i = 2; n > 1 && i < result.length; i++) {
                while (n % i == 0) {
                    result[i]++;
                    n /= i;
                }
            }
            return result;

        }
    }
}


Measured memory_bytes: 24660