View Compilation Error

0_0_31827276_24870.cpp: In function 'int main()':
0_0_31827276_24870.cpp:7:21: error: unable to find numeric literal operator 'operator""i'
   day[i]=(day[i-1]*(4i-2))/(i+1);
                     ^
0_0_31827276_24870.cpp:7:21: note: use -std=gnu++11 or -fext-numeric-literals to enable more built-in suffixes