7
max(a[1],a[2])
max(a[1],max(a[2],a[3]))
max(a[1],min(a[2],a[3]))
max(a[1],max(a[2],max(a[3],a[4])))
max(a[1],max(a[2],min(a[3],a[4])))
max(a[1],min(a[2],max(a[3],a[4])))
max(a[1],min(a[2],min(a[3],a[4])))