The following statements (S1 to S4) pertain to a compression member.

S1: The effective length depends on the boundary conditions of member at ends.

S2: The elastic critical stress in compression decreases with decrease in slenderness ratio.

S3: The ratio of the effective length to the radius of gyration of the member is termed as slenderness ratio of member.

S4: The elastic critical stress in compression is independent of the slenderness ratio.

Identify the correct statements.