Assets/airtime.cs(18,20): error CS1525: Unexpected symbol `if'

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class airtime : MonoBehaviour {

// Use this for initialization
float sayac = 0;
float combo = 0;
public bool on_air = false;
void Start() {

}

// Update is called once per frame
void Update() {

    if (sayac > if) 
        {
            on_air = true;
            combo++;
            sayac = 0;
            Debug.Log("Havada":+combo);
        }
    sayac += Time.deltaTime;
}
void OnCollision2D(Collision2D coll)
{
    if (coll.gameObject.tag == "Player" || coll.gameObject.tag == "teker")
    {
        combo = 0;
        sayac = 0;
        on_air = false;
    }
}
void OnCollisionStay2D(Collision2D coll)
{
    if (coll.gameObject.tag == "Player" || coll.gameObject.tag == "teker")
    {
        combo = 0;
        sayac = 0;
        on_air = false;
    }
}

What is the problem? Cna you help me please?

void Update() {
if (sayac > if)

here is some problem. Can you help me please?