import strutils, math


proc nextString: string =
    result = ""
    while not endOfFile stdin:
        let nextChar = readChar stdin
        case nextChar
        of '\r':
            discard
        of "\n"[0], ' ':
            break
        else:
            add result, nextChar


proc nextInt: int =
    return parseInt nextString()


proc judge(n: int): bool =
    for i in 2 .. int.high:
        if i ^ 2 > n:
            return
        if n mod i == 0:
            return true


proc main: void =
    let n = nextInt()
    writeLine stdout, ["NO", "YES"][int judge n]


when isMainModule:
    main()