Calculadora

def app():
    op = 0
    a=int(input("Ingrese valor: "))
    while op != 5:
        op=int(input("1 = Suma \n2 = Resta \n3 = Multiplicación \n4 = Division \n5 = Igual  \nIngrese operación: "))
        if op == 1:
            b=int(input("Ingrese valor: "))
            c=a+b
            a=c
            print(int(c))
        elif op == 2:
            b=int(input("Ingrese valor: "))
            c=a-b
            a=c
            print(int(c))
        elif op == 3:
            b=int(input("Ingrese valor: "))
            c=a*b
            a=c
            print(int(c))
        elif op == 4:
            b=int(input("Ingrese valor: "))
            c=a/b
            a=c
            print(int(c))
        elif op == 5:
            int(c)
            print("El resultado es: "+str(c))