let n = Int(readLine()!)!
var m = [Int]()
for _ in 1...n{
    let s = String(readLine()!)
    if s.contains(" "){
        break
    }else{
        m += [Int(s)!]
    }
}
if m == []{
    print("assert")
}else{
    let l = Array(Set([m[0]+m[1],m[0]+m[2],m[1]+m[2]])).sorted(by:>)
    print(l[1])
}