GAMS: Setting one variable to be equal to the second smallest of another vector variable

Question

SET i /i1 * i10/ ; 

VARIABLES
x(i)
y
;  

I have an optimization (mip) problem where i need my control variable y to be equal to the second smallest number of x. How can I create an equation to do that?

EQUATIONS
myconstraint ;

myconstraint .. y =E= (second smallest element of x) ;