not running port

the pi is showing this text: Explorer HAT Pro detected...
Traceback (most recent call last):
File "app.py", line 36, in
app.run(host='0.0.0.0', port=80)
File "/usr/lib/python2.7/dist-packages/flask/app.py", line 841, in run
run_simple(host, port, self, **options)
File "/usr/lib/python2.7/dist-packages/werkzeug/serving.py", line 708, in run_simple
inner()
File "/usr/lib/python2.7/dist-packages/werkzeug/serving.py", line 670, in inner
fd=fd)
File "/usr/lib/python2.7/dist-packages/werkzeug/serving.py", line 564, in make_server
passthrough_errors, ssl_context, fd=fd)
File "/usr/lib/python2.7/dist-packages/werkzeug/serving.py", line 476, in init
HTTPServer.init(self, (host, int(port)), handler)
File "/usr/lib/python2.7/SocketServer.py", line 417, in init
self.server_bind()
File "/usr/lib/python2.7/BaseHTTPServer.py", line 108, in server_bind
SocketServer.TCPServer.server_bind(self)
File "/usr/lib/python2.7/SocketServer.py", line 431, in server_bind
self.socket.bind(self.server_address)
File "/usr/lib/python2.7/socket.py", line 228, in meth
return getattr(self._sock,name)(*args)
socket.error: [Errno 98] Address already in use

Explorer HAT exiting cleanly, please wait...
Stopping flashy things...
Stopping user tasks...
Cleaning up...
Goodbye!
Segmentation fault