If a₁+a₂=1, a₂+a₃=2, a₃+a₄=3, a₄+a₅=4,....a₅₀+a₅₁=50 and a₅₁+a₁=51, then what is the sum of a₁, a₂, a₃,....., a₅₁ ?
A. 663
B. 1326
C. 1076
D. 538
E. 665
