10
min(max(max(a[1],a[2]),a[3]),a[4])
min(max(a[1],max(a[2],a[3])),a[4])
min(max(a[1],a[2]),max(a[3],a[4]))
min(a[1],max(max(a[2],a[3]),a[4]))
min(a[1],max(a[2],max(a[3],a[4])))
min(max(min(a[1],a[2]),a[3]),a[4])
min(max(a[1],min(a[2],a[3])),a[4])
min(max(a[1],a[2]),min(a[3],a[4]))
min(a[1],max(min(a[2],a[3]),a[4]))
min(a[1],max(a[2],min(a[3],a[4])))