program percent

 implicit none
 integer :: year,i
 real(4) :: yen
 real(8) :: x

 read*,x

 year=1
 yen=100

 do i=1,10000000
  yen=yen*1.01
  if(yen>=x) exit
  year=year+1
  yen=aint(yen)
 end do

 print*,year

end program percent
