View Compilation Error

0_0_22360025_29616.cpp: In function 'int main()':
0_0_22360025_29616.cpp:11:5: error: 'cin' was not declared in this scope
     cin>>t;
     ^
0_0_22360025_29616.cpp:19:19: error: 'sort' was not declared in this scope
         sort(a,a+n);
                   ^
0_0_22360025_29616.cpp:21:42: error: 'upper_bound' was not declared in this scope
             t+=upper_bound(a+i,a+n,a[i]+k)-(a+i)-1;
                                          ^