How to make keypad timer Switch

1#include <Keypad.h>
2
3int relay_pin = A0;
4
5long int timer =  0;
6
7const int ROW_NUM = 4; //four rows
8const int COLUMN_NUM = 3; //three  columns
9
10char keys[ROW_NUM][COLUMN_NUM] = {
11  {'1', '2', '3'},
12  {'4',  '5', '6'},
13  {'7', '8', '9'},
14  {'*', '0', '#'}
15};
16
17byte pin_rows[ROW_NUM]  = {9, 8, 7, 6}; //connect to the row pinouts of the keypad
18byte pin_column[COLUMN_NUM]  = {5, 4, 3}; //connect to the column pinouts of the keypad
19
20Keypad keypad  = Keypad( makeKeymap(keys), pin_rows, pin_column, ROW_NUM, COLUMN_NUM );
21
22
23String  input_value;
24
25void setup() {
26
27  pinMode(relay_pin, OUTPUT);
28
29
30  Serial.begin(9600);
31  input_value.reserve(32); // maximum input characters  is 33, change if needed
32}
33
34void loop() {
35  char key = keypad.getKey();
36
37  if (key) {
38    Serial.println(key);
39
40    if (key == '*') {
41      input_value  = ""; // clear input value
42    } else if (key == '#') {
43
44      timer  = input_value.toInt();
45
46
47     timer = timer * 1000; //time in seconds
48      //timer = timer * 1000 * 60; //time in minuts
49     // timer = timer * 1000  * 60 * 60; //time in hours
50
51      digitalWrite(relay_pin, HIGH);
52      Serial.println("relay  on");
53
54      delay(timer);
55      digitalWrite(relay_pin, LOW);
56      Serial.println("relay  off");
57
58      timer = 0;
59
60
61
62      input_value = ""; // clear  input value
63    } else {
64      input_value += key; // append new character  to input value string
65    }
66  }
67}
68