View Compilation Error

0_0_33507528_19040.cpp: In function 'int main()':
0_0_33507528_19040.cpp:73:2: error: 'cin' was not declared in this scope
  cin>>n;
  ^
0_0_33507528_19040.cpp:85:4: error: 'cout' was not declared in this scope
    cout<<maxnum<<endl;
    ^
0_0_33507528_19040.cpp:85:18: error: 'endl' was not declared in this scope
    cout<<maxnum<<endl;
                  ^