View Compilation Error

0_0_35192092_20990.cpp: In function 'int main()':
0_0_35192092_20990.cpp:70:18: error: unable to find numeric literal operator 'operator""n'
   for(int i=1;i<=2n;i++)a[i]='G';
                  ^
0_0_35192092_20990.cpp:70:18: note: use -std=gnu++11 or -fext-numeric-literals to enable more built-in suffixes