View Compilation Error

0_0_32812919_22941.cpp: In function 'int main()':
0_0_32812919_22941.cpp:84:31: error: 'scanf' was not declared in this scope
      while(scanf("%d%d",&N ,&M)){
                               ^
0_0_32812919_22941.cpp:116:11: error: 'set' was not declared in this scope
           set<int>ans ;
           ^
0_0_32812919_22941.cpp:116:15: error: expected primary-expression before 'int'
           set<int>ans ;
               ^
0_0_32812919_22941.cpp:118:11: error: 'ans' was not declared in this scope
           ans.clear() ;
           ^
0_0_32812919_22941.cpp:124:55: error: 'printf' was not declared in this scope
           printf("Case #%d: %d\n" , cas++ , ans.size()) ;
                                                       ^