diff --git a/src/main.py b/src/main.py
new file mode 100644
index 0000000..9a73136
--- /dev/null
+++ b/src/main.py
@@ -0,0 +1,59 @@
+#!/bin/python3
+from queue import Queue
+
+class NoServerFreeError(Exception):
+    def __init__(self, message="No server free"):
+        self.message = message
+        super().__init__(self.message)
+
+class Request:
+    def __init__(self, lambda_val, current_time):
+        # exponential distribution, parameter λ
+        interval = random.expovariate(self.lambda_val)
+        new_time = self.current_time + interval
+
+        self.arrival_time = new_time
+        self.category = 1
+
+
+class Server_cluster:
+    def __init__(self, cluster_size, category, service_rate):
+        self.category = category
+        self.cluster_size = cluster_size
+        self.finish_time = [0.0]*cluster_size
+
+    def process_request(self, request, current_time):
+        free_servers = [i for i in range(self.cluster_size) if self.finish_time[i] <= current_time]
+        if not free_servers:
+            raise NoServerFreeError()
+        else:
+            interval = random.expovariate(self.service_rate)
+            finish = current_time + interval
+            self.finish_time[free_servers[0]] = finish
+
+
+class Simulation:
+    def __init__(self, C, lambda_val):
+        # C clusters of K servers
+        self.C = C
+        self.K = 12 // C
+        # service rate exponential distribution parameter
+        service_rates = {1: 4/20, 2:7/20, 3:10/20, 6:14/20}
+        self.service_rate = service_rates[C]
+        # router request processing time
+        self.router_processing_time = (C - 1) / C
+        # λ
+        self.lambda_val = lambda_val
+
+        self.router_queue = Queue(maxsize = 100)
+        self.router_state = 'idle'  # 'idle', 'processing', 'blocked'
+
+        self.event_queue = Queue() # (arrival_time, category)
+        self.current_time = 0.0
+
+        self.total_requests = 0
+        self.lost_requests = 0
+        self.response_times = []
+
+
+