Maria + Andrei = 324 castane
Andrei + Costel = 362 castane
Maria + Costel = 321 castane
Maria + Andrei + Costel = 324 + 362 + 321
= 1007 castane
324 + C = 1007 castane
C = 1007 - 324
C = 683 castane
M + 362 = 1007 castane
M = 1007 - 362
M = 645 castane
321 + A = 1007 castane
A = 1007 - 321
A = 686 castane