import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.NoSuchElementException;

public class Main{
	static FastScanner sc = new FastScanner();
	static PrintWriter out = new PrintWriter(System.out);
	static int d;
	static int g;
	static int p[];
	static long c [];
	static long [][] dp;
	static int max;
	
	public static void main(String[] args) {
		d = sc.nextInt();
		g = sc.nextInt();
		
		read(d);
		
		dp = new long [d+1][max+1];
		boolean seen [][] = new boolean [d+1][max+1];
		
		
		for (int i=1; i<=d; i++) {
			seen[i-1][0]=true;
			
			for (int j=1; j<=p[i]; j++) {
				long score = i*j+Math.max(0, (j-p[i]+1)*c[i]);
				
				for (int s=0; s+j<=max; s++) {
					if (seen[i-1][s]) 
						dp[i][s+j] = Math.max(dp[i-1][s]+score, dp[i-1][s+j]);
					
					else 
						dp[i][s+j] = dp[i-1][s+j];
					
					seen[i][s+j]=true;
				}
				
			}	
		}
		
		int ind = 0;
		for (long i: dp[d]) {
			if (i>=(g/100))
				break;
			ind++;
		}
		
		out.println(ind);
        out.flush();
	}
	
	static void read (int i) {
		p = new int [i+1];
		c = new long [i+1];
		
		max = 0;
		for (int j=1; j<=d; j++) {
			p[j] = sc.nextInt();
			c[j] = (sc.nextLong()/100);
			max+=p[j];
		}
	}
	
	
	
	static class FastScanner {
	    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 static boolean isPrintableChar(int c) {
	      return 33 <= c && c <= 126;
	    }

	    private void skipUnprintable() {
	      while (hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
	    }

	    public boolean hasNext() {
	      skipUnprintable();
	      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() {
	      return (int) nextLong();
	    }

	    public int[] nextIntArray(int N, boolean oneBased) {
	      if (oneBased) {
	        int[] array = new int[N + 1];
	        for (int i = 1; i <= N; i++) {
	          array[i] = sc.nextInt();
	        }
	        return array;
	      } else {
	        int[] array = new int[N];
	        for (int i = 0; i < N; i++) {
	          array[i] = sc.nextInt();
	        }
	        return array;
	      }
	    }

	    public long[] nextLongArray(int N, boolean oneBased) {
	      if (oneBased) {
	        long[] array = new long[N + 1];
	        for (int i = 1; i <= N; i++) {
	          array[i] = sc.nextLong();
	        }
	        return array;
	      } else {
	        long[] array = new long[N];
	        for (int i = 0; i < N; i++) {
	          array[i] = sc.nextLong();
	        }
	        return array;
	      }
	    }
	  }

	}	 




		

Measured memory_bytes: 23252