View Compilation Error

0_0_11528114_26289.cpp: In function `int main()':
0_0_11528114_26289.cpp:32: error: `set' undeclared (first use this function)
0_0_11528114_26289.cpp:32: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_11528114_26289.cpp: In function `int find(int)':
0_0_11528114_26289.cpp:48: error: `set' undeclared (first use this function)
0_0_11528114_26289.cpp: In function `void union_set(int, int)':
0_0_11528114_26289.cpp:63: error: `set' undeclared (first use this function)