View Compilation Error

0_0_32898996_2954.cpp:5:1: error: expected unqualified-id before '?' token
 ?
 ^
0_0_32898996_2954.cpp: In function 'int find(int)':
0_0_32898996_2954.cpp:9:12: error: 'f' was not declared in this scope
     return f[x] == x ? x : f[x] = find(f[x]);
            ^
0_0_32898996_2954.cpp: At global scope:
0_0_32898996_2954.cpp:11:1: error: expected unqualified-id before '?' token
 ?
 ^