abcd+abc+bcd+cda+dab+ab+bc+cd+da+ac+bd+a+b+c+d=2009 a+b+c+d=? It's urgent,

abcd+abc+bcd+cda+dab+ab+bc+cd+da+ac+bd+a+b+c+d=2009 a+b+c+d=? It's urgent,

When you see ABCD + ABC + BCD + CDA + DAB + AB + BC + CD + Da + AC + BD + A + B + C + D, you can think of the above formula plus 1, that is, ABCD + ABC + BCD + CDA + DAB + AB + BC + CD + Da + AC + BD + A + B + C + D + 1
(a+1)x(b+1)x(c+1)x(d+1)
That is, (a + 1) x (B + 1) x (c + 1) x (D + 1) = 2010
If a, B, C and D are all positive integers, you can try to make a + 1 = 2, B + 1 = 10, C + 1 = 2, D + 1 = 5
So a + B + C + D = 15