f(x+4)=1/f(x+2)=f(x)
so f(119)=f(120-1)=f(-1)=f(1)
let x=-1 from f(x+2)=1/f(x) we have f(1)=1/f(-1)=1/f(1)
because f(x)>0 so f(119)=f(1)=1