program main
     implicit none
     integer(8) ::su=0
     integer(8),allocatable,dimension(:)::c,d,e
     integer n,i
     read(*,*)n
     allocate(c(n),d(n),e(n))
     do i=1,n
          read(*,*)c(i),d(i)
     enddo
     do i=1,n
        c(i)=(c(i)+1)/2
        e(i)=mod(c(i),1000000007)*mod(d(i),1000000007)
     enddo
     do i=1,n
          su=mod(su+e(i),1000000007)
     enddo
     write(*,*)su
end program main