program Fibon
    implicit none
    integer :: n, fibonacci
    write (*,'(a$)') 'Enter n:'
    read (*,*) n
    write (*,'(i10)') fibonacci(n)
end program Fibon

recursive function fibonacci(m) result(fibo)
    integer :: m, fibo
    if ( (m == 1) .or. (m == 2) ) then
        fibo = 1
    else
        fibo = fibonacci(m-1) + fibonacci(m-2)
    end if
end function