Raspberry Pi Gui alarm clock code error: invalid literal for int() with base 10: '2,'

self.alarm_h = int(alarm_time[19:21]) #value of hour is sorted in index value of 19 and 20
ValueError: invalid literal for int() with base 10: '2,' 

import sys

import time

from PyQt4 import QtCore, QtGui #PyQt4 is used for designing the GUI

from time import strftime # To get time from Raspberry pi

try:

    _fromUtf8 = QtCore.QString.fromUtf8

except AttributeError:
    def _fromUtf8(s):

       return s

try:
    _encoding = QtGui.QApplication.UnicodeUTF8

    def _translate(context, text, disambig):
        return QtGui.QApplication.translate(context, text, disambig, _encoding)

except AttributeError:

    def _translate(context, text, disambig):
        return QtGui.QApplication.translate(context, text, disambig)

class Ui_MainWindow(object):

    def setupUi(self, MainWindow):

        self.alarm_h = 0
        self.alarm_m = 0

        MainWindow.setObjectName(_fromUtf8("MainWindow"))
        MainWindow.resize(676, 439)

        self.centralwidget = QtGui.QWidget(MainWindow)
        self.centralwidget.setObjectName(_fromUtf8("centralwidget"))
        self.gridLayout = QtGui.QGridLayout(self.centralwidget)
        self.gridLayout.setObjectName(_fromUtf8("gridLayout"))
        self.label = QtGui.QLabel(self.centralwidget)

        font = QtGui.QFont()
        font.setPointSize(14)
        self.label.setFont(font)
        self.label.setObjectName(_fromUtf8("label"))
        self.gridLayout.addWidget(self.label, 3, 0, 1, 1)

        self.Time_LCD = QtGui.QLCDNumber(self.centralwidget)
        self.Time_LCD.setObjectName(_fromUtf8("Time_LCD"))
        self.Time_LCD.setDigitCount(8)
        self.Time_LCD.display(strftime("%H"+":"+"%M"+":"+"%S")) #get time from Pi and display it 
        self.gridLayout.addWidget(self.Time_LCD, 1, 0, 1, 3)

        self.timer = QtCore.QTimer(MainWindow)
        self.timer.timeout.connect(self.Time)
        self.timer.start(1000)

        current_time = QtCore.QTime()
        self.Set_Time = QtGui.QTimeEdit(self.centralwidget)
        self.Set_Time.setObjectName(_fromUtf8("Set_Time"))
        self.Set_Time.setTime(current_time.currentTime())
        self.gridLayout.addWidget(self.Set_Time, 2, 0, 1, 1)


        self.pushButton = QtGui.QPushButton(self.centralwidget)
        self.pushButton.setObjectName(_fromUtf8("pushButton"))
        self.pushButton.clicked.connect(self.button_pressed)
        self.gridLayout.addWidget(self.pushButton, 2, 1, 1, 1)
        MainWindow.setCentralWidget(self.centralwidget)

        self.menubar = QtGui.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 676, 21))
        self.menubar.setObjectName(_fromUtf8("menubar"))
        MainWindow.setMenuBar(self.menubar)

        self.statusbar = QtGui.QStatusBar(MainWindow)
        self.statusbar.setObjectName(_fromUtf8("statusbar"))
        MainWindow.setStatusBar(self.statusbar)

        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

#End of code from Qt Designer

    def retranslateUi(self, MainWindow): #update the GUI window 
        print("Dispay Re-translated")
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow", None))
        self.label.setText(_translate("MainWindow", "Alarm curretly Turned off", None))
        self.pushButton.setText(_translate("MainWindow", "Set Alarm", None))

    def Time(self): #Function to compare current time with set time 
        self.Time_LCD.display(strftime("%H"+":"+"%M"+":"+"%S"))
        self.current_h = int (strftime("%H"))
        self.current_m = int (strftime("%M"))

        if (self.current_h == self.alarm_h) and (self.current_m == self.alarm_m) and ((int(strftime("%S"))%15) == 0): #if the both time match 
            print("ALARM ON!!!!!")

            message1 = " The time is " + str(self.alarm_h) + " : " + str(self.alarm_m) + " on " + strftime("%A")
            message = "Sir, Good morning.. This is your wake up Alarm." + message1

            self.label.setText(_translate("MainWindow",message1, None)) #display the message on GUI screen            
            time.sleep(1)

    def button_pressed(self): #when set alarm button is pressed 
        print("Button Pressed")
        alarm_time = str(self.Set_Time.time())

        self.alarm_h = int(alarm_time[19:21]) #value of hour is sotred in index value 19 and 20
        self.alarm_m = int (alarm_time[23:25]) #value of minute is sotred in index value 23 and 24

        message = "Alarm is set at " + str(self.alarm_h) + " hours " + str(self.alarm_m) + " minutes"
        self.label.setText(_translate("MainWindow", message, None)) #display the message on GUI screen  

if __name__ == "__main__": #main function 

    app = QtGui.QApplication(sys.argv)
    MainWindow = QtGui.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())