import os
import struct
def main():
    a=os.popen('ip a | grep "scope global"').read()
    a=a.split("/")
    ip = a[0].split(" ")[5]
    masqueRaw = a[1].split(" ")[0]
    masque = []
    cpt=0
    for i in range(4):
        temp=""
        for j in range(8):
            cpt+=1
            if cpt<=int(masqueRaw):temp+="1"
            else:temp+="0"
        masque.append(temp)
    ip=ip.split(".")
    masque = list(map(lambda x: int(x,2),masque))
    network=""
    for i in range(4):
        temp=int(ip[i]) & masque[i]
        network+=str(temp)
        if i<4: network+="."
    sys.exit(network)
    return network