Possibility 2
y = a [ i ] + b [ i ] NEW_LINE if i + 1 < n : NEW_LINE INDENT y += b [ i + 1 ] NEW_LINE DEDENT if y == x : NEW_LINE INDENT a [ i ] = y NEW_LINE b [ i ] = 0 NEW_LINE if i + 1 < n : b [ i + 1 ] = 0 NEW_LINE continue NEW_LINE DEDENT