Getting wrong output for Lotka Volterra Model in Python (Jupyter) using RK4 to solve , HOw much precision can affect?

Question

I am new to coding. i don't know what is wrong with this code. I expect to get periodic solution for both x and y variable i.e. prey and predator with respect ot time but i am getting oscillations where amplitude of both goes on increasing with time. where is the problem.

import matplotlib.pyplot as plt

def x_dot(x,y):
    return a*x-b*x*y
def y_dot(x,y):
    return -c*y+d*x*y


h=0.01
a=1.1
b=0.1
c=1.4
d=0.1
def f(x,y):
    
    t=0
    x_values=[x]
    y_values=[y]
   
    t_values=[t]
    while(t<500):
# RK4 Method to solve differential equations    
        k1=x_dot(x,y)
        l1=y_dot(x,y)
        
        k2=x_dot(x+(h*k1)/2,y+(k1*h)/2)
        l2=y_dot(x+(h*l1)/2,y+(l1*h)/2)
       
        k3=x_dot(x+(h*k2)/2,y+(k2*h)/2)
        l3=y_dot(x+(h*l2)/2,y+(l2*h)/2)
          
        k4=x_dot(x+h*k3,y+h*k3)
        l4=y_dot(x+h*l3,y+h*l3)
       
    
        t=(t+h)
# Appending calculated values in the respective list    
        t_values.append(t)
        x=x+h*(k1/6+k2/3+k3/3+k4/6)
        x_values.append(x)
        y=y+h*(l1/6+l2/3+l3/3+l4/6)
        y_values.append(y)
       

    return x_values,y_values,t_values 

x_values,y_values,t_values= f(1,1.3)   #calling the function with intial values
plt.plot(t_values,x_values)