View Compilation Error

0_0_32512409_25982.cpp: In function 'int find(int)':
0_0_32512409_25982.cpp:22:13: error: 'f' was not declared in this scope
 { return x==f[x]?f[x]=find(f[x]); }
             ^
0_0_32512409_25982.cpp:22:33: error: expected ':' before ';' token
 { return x==f[x]?f[x]=find(f[x]); }
                                 ^
0_0_32512409_25982.cpp:22:33: error: expected primary-expression before ';' token