Răspuns:
a+b+c+d=
b=1998
a=1997
c=1999
d=2000
1997+1998+1999+2000=7994
b=7894
a=7893
c=7895
d=7896
7893+7894+7895+7896=31578
b=7984
a=7983
c=7985
d=7986
7983+7984+7985+7986=31938
b=7994
a=7993
c=7995
d=7996
7993+7994+7995+7996=31978
b=7884
a=7883
c=7885
d=7886
=31538
