View Compilation Error

0_0_15987384_26913.cpp: In function 'void qq(char*)':
0_0_15987384_26913.cpp:4:14: error: 'strlen' was not declared in this scope
  len=strlen(a)-1;
              ^
0_0_15987384_26913.cpp: In function 'int main()':
0_0_15987384_26913.cpp:20:8: error: 'cin' was not declared in this scope
  while(cin>>a>>b)
        ^
0_0_15987384_26913.cpp:22:15: error: 'strlen' was not declared in this scope
   len=strlen(a);
               ^
0_0_15987384_26913.cpp:37:16: error: 'strcmp' was not declared in this scope
   if(strcmp(a,b))
                ^
0_0_15987384_26913.cpp:38:4: error: 'cout' was not declared in this scope
    cout<<"NO"<<endl;
    ^
0_0_15987384_26913.cpp:38:16: error: 'endl' was not declared in this scope
    cout<<"NO"<<endl;
                ^
0_0_15987384_26913.cpp:40:4: error: 'cout' was not declared in this scope
    cout<<"YES"<<endl;
    ^
0_0_15987384_26913.cpp:40:17: error: 'endl' was not declared in this scope
    cout<<"YES"<<endl;
                 ^