program main implicit none integer*8::C,N,i,j,ABGCD read *,N if(MOD(N,2).eq.0) then ABGCD = gcd(2*N,1+N) N = N/2 else ABGCD = gcd(N,(1+N)/2) end if C = 1 call sub(ABGCD,C) call sub(N,C) print '(i0)',C contains subroutine sub(N,c) integer*8,intent(inout)::N,C integer*8::i,j,SQRTN integer*1,allocatable::insuu(:) SQRTN =INT(SQRT(DBLE(N))) allocate(insuu(SQRTN)) insuu = 0 do i=2,SQRTN if(insuu(i).eq.1) continue do j=i+i,SQRTN,i insuu(j) = 1 end do if(MOD(N,i).eq.0) then do C = (i+1)*C N = N/i if(MOD(N,i).ne.0) exit end do end if if(N.eq.1) exit end do if(N.ne.1) C = C*(1+N) deallocate(insuu) end subroutine sub recursive function gcd(a,b) result(c) implicit none integer*8::a,b,c if(b.eq.0) then c = a else c = gcd(b,MOD(a,b)) end if end function gcd end program main