View Compilation Error

0_0_29942209_29301.cpp:4:19: error: declaration does not declare anything [-fpermissive]
 typedef long long __int128;
                   ^
0_0_29942209_29301.cpp:13:1: error: 'IT' does not name a type
 IT n;
 ^
0_0_29942209_29301.cpp:17:1: error: 'IT' does not name a type
 IT read()
 ^
0_0_29942209_29301.cpp:44:11: error: 'IT' was not declared in this scope
 int sqrt3(IT n)
           ^
0_0_29942209_29301.cpp:45:1: error: expected ',' or ';' before '{' token
 {
 ^