Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Serial & Branch | Seaman | Mechanical | Secretariat | Supply | Electrical | Radio Electrical | Regulating | Medical |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1.0 | OD ( Ordinary Seaman ) | ME II | WTR II | SA II | EN II | REN II | PM II | MA II |
| 2.0 | AB ( Able Seaman ) | ME I | WTR I | SA I | EN I | REN I | PM I | MA I |
| 3.0 | LS ( Leading Seaman ) | LME | LWTR | LSA | LEN | LREN | LPM | LMA |
| 4.0 | PO ( Petty Officer ) | ERA-IV | PO(W) | PO(S) | EA-IV | REA-IV | PO(R) | PO(Med) |
| 5.0 | CPO ( Chief Petty Officer ) | ERA-I/II/III | CPO(W) | CPO(S) | EA-I/II/III | REA-I/II/III | CPO(REG) | CPO(Med) |
| 6.0 | SCPO ( Senior Chief Petty Officer ) | SCPO(E),CERA | SCPO(W) | SCPO(S) | SCPO(L),CEA | SCPO(R),CREA | SCPO(Reg) | SCPO(Med) |
| 7.0 | MCPO ( Master Chief Petty Officer ) | MCPO(E) | MCPO(S) | MCPO(S) | MCPO(L) | MCPO(R) | MCPO(Reg) | MCPO(Med) |
| 8.0 | Honorary Sub Lieutenant(X) | Hon S Lt(E) | Hon S Lt(S) | Hon S Lt(S) | Hon S Lt(L) | Hon S Lt(R) | Hon S Lt(Reg) | Hon S Lt(W/M) |
Question:
How many serial branches have radio electrial = rea-iv?
Answer:
1.0