View Compilation Error

0_0_28961576_1954.cpp: In function 'int main()':
0_0_28961576_1954.cpp:13:9: error: unable to find numeric literal operator 'operator""b'
   if(a<=2b){
         ^
0_0_28961576_1954.cpp:13:9: note: use -std=gnu++11 or -fext-numeric-literals to enable more built-in suffixes