View Compilation Error

0_0_20028664_29753.cpp: In function 'bool cmp(person, person)':
0_0_20028664_29753.cpp:23:45: error: 'strcmp' was not declared in this scope
  else if (a.num==b.num&&strcmp(a.name,b.name))
                                             ^
0_0_20028664_29753.cpp: In function 'int main()':
0_0_20028664_29753.cpp:49:2: error: 'cin' was not declared in this scope
  cin>>n;
  ^
0_0_20028664_29753.cpp:60:3: error: 'cout' was not declared in this scope
   cout<<a[0].name<<endl;
   ^
0_0_20028664_29753.cpp:60:20: error: 'endl' was not declared in this scope
   cout<<a[0].name<<endl;
                    ^