def uc(a,b):
    while a!=b:
        if a>b:
            a-=b
        else:
            b-=a
    return a
a,b = map(int,input("Nhap 2 so a,b: ").split())
print("Uoc chung cua",a,"va",b,"la:",uc(a,b))

Code:

from math import gcd
from kivy.app import App
from kivy.uix.textinput import TextInput
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.uix.boxlayout import BoxLayout
class Main(App):
    def build(self):
        main_layout = BoxLayout(orientation="vertical")
        self.enter_a = Label(text="Enter a: ")
        self.input_a = TextInput()
        self.enter_b = Label(text="Enter b: ")
        self.input_b = TextInput()
        self.result = Label(text="")
        submit = Button(text="Submit")
        main_layout.add_widget(self.enter_a)
        main_layout.add_widget(self.input_a)
        main_layout.add_widget(self.enter_b)
        main_layout.add_widget(self.input_b)
        main_layout.add_widget(submit)
        main_layout.add_widget(self.result)
        submit.bind(on_press=self.solve)
        return main_layout
    def solve(self, instance):
        a = self.input_a.text
        b = self.input_b.text
        try:
            self.result.text = str(gcd(int(a),int(b)))
        except Exception as e:
            self.result.text = str(e)
if __name__ == "__main__":
    app = Main()
    app.run()