foo.cpp:40:7: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
  main()
       ^
foo.cpp: In function 'int main()':
foo.cpp:48:51: error: 'printf' was not declared in this scope
  if (ss<=s) printf("Need %.2f miles of cable\n",ss); else cout<<"Impossible"<<endl;
                                                   ^