a1,a2,⋯,a2003 are integers such that ∣a1∣=1 and ∣ai+1∣=∣ai+1∣(1≤i≤2002). What is the minimal value of ∣a1+a2+⋯+a2003∣?<spanclass=′latex−bold′>(A)</span>4<spanclass=′latex−bold′>(B)</span>34<spanclass=′latex−bold′>(C)</span>56<spanclass=′latex−bold′>(D)</span>65<spanclass=′latex−bold′>(E)</span>None of the preceding