View Compilation Error

0_0_29608762_31031.cpp: In function 'int main()':
0_0_29608762_31031.cpp:11:12: error: unable to find numeric literal operator 'operator""f2'
       f=f1+2f2;
            ^
0_0_29608762_31031.cpp:11:12: note: use -std=gnu++11 or -fext-numeric-literals to enable more built-in suffixes