View Compilation Error

0_0_32924132_28103.cpp: In function 'int main()':
0_0_32924132_28103.cpp:25:40: error: 'upper_bound' was not declared in this scope
     {it=upper_bound(q.begin(),q.end(),x);q.insert(it,x);} 
                                        ^
0_0_32924132_28103.cpp:40:40: error: 'upper_bound' was not declared in this scope
      it=upper_bound(q.begin(),q.end(),x);
                                        ^