View Compilation Error

0_0_21648894_12081.cpp: In function 'int main()':
0_0_21648894_12081.cpp:68:30: error: unable to find numeric literal operator 'operator""f'
   if(p == q) printf("%.7f\n",0f);
                              ^
0_0_21648894_12081.cpp:68:30: note: use -std=gnu++11 or -fext-numeric-literals to enable more built-in suffixes