program sample
    implicit none  !二分探索
    integer(8) ::c,i,j,m(12),n,k,a1,b1,c1
    character::a(2)
    character(len=1),allocatable::s(:)
    character(len=1)::t(1:26)
    t=(/'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'/)
    read(*,*) n

    do i=1,12
        m(i)=0
    end do
    j=0
    do while (n>0)
        j=j+1
        m(j)=mod(n,26)
        if (m(j)==0)then
            m(j)=26
        end if
        
        n=n/26
    end do
    allocate(s(j))
    do i=1,j
        s(j+1-i)=t(m(i))
    end do
    write(*,'(a,a,a,a,a,a,a,a,a,a,a,a,a)')s
    

    
    stop

end program sample
  

