program test
implicit none
integer(8) :: mondai_max,mondai,point,ii,i,j,k,m,n,d,g,p(100),c(100),comp(10) = 0,needs
read(*,*) d,g
do i=1,d
	read(*,*) p(i),c(i)
enddo

mondai_max = 10**9

do ii = 1,2**d
	
	mondai = 0
	point = 0
	
	do i=1,d
	if(comp(i) == 1) then
		mondai = mondai + p(i)
		point = point + 100*i*p(i) + c(i)
	endif
	enddo
	if(point >= g) then
	mondai_max = min(mondai_max,mondai)
	goto 10
	endif

	do i=d,1,-1
		if (comp(i) == 1) then
			continue
		else if(point+(p(i)-1)*100*i>=g) then
			needs = ceiling((g - point) / (100. * i))
			mondai = mondai + needs
			
			mondai_max = min(mondai_max,mondai)
			goto 10
		else
			mondai = mondai + p(i)-1
			point = point + 100*i*(p(i)-1)
		endif
	enddo

10 continue

	comp(1) = comp(1) + 1
	do i=1,d-1
	if(comp(i) == 2) then
		comp(i) = 0
		comp(i+1) = comp(i+1) + 1
	endif
	enddo

enddo

write(*,*) mondai_max

end program