```go
package main

import "fmt"

func main() {
    var n int
    fmt.Scan(&n)
    
    x := make([]int, n)
    for i := 0; i < n; i++ {
        fmt.Scan(&x[i])
    }
    
    for i := 0; i < n-1; i++ {
        for j := i + 1; j < n-1; j++ {
            a, b := x[i], x[i+1]
            if a > b {
                a, b = b, a
            }
            
            c, d := x[j], x[j+1]
            if c > d {
                c, d = d, c
            }
            
            cIn := a < c && c < b
            dIn := a < d && d < b
            aIn := c < a && a < d
            bIn := c < b && b < d
            
            if cIn != dIn && aIn != bIn {
                fmt.Println("yes")
                return
            }
        }
    }
    
    fmt.Println("no")
}
```