4 Tables are required at minimum
Reason:
R3 can merge with E2
E2R3 can merge with R1
R1E2R3 cannot merge with E1, Hence separate table is required for R1E2R3
Now R4 cannot merge with E3, Hence separate table is required for R4
E3 can merge with R2
E3R2 can merge with E1, Hence separate table is required for E3R2
E1 has a multivalued attribute, Hence separate table is required for it.