View Compilation Error

0_0_18020588_30111.cpp:14:4: error: stray '\' in program
    /\n=(b+11c)*k+2*a
    ^
0_0_18020588_30111.cpp: In function 'int main()':
0_0_18020588_30111.cpp:14:4: error: expected primary-expression before '/' token
0_0_18020588_30111.cpp:14:11: error: unable to find numeric literal operator 'operator""c'
    /\n=(b+11c)*k+2*a
           ^
0_0_18020588_30111.cpp:14:11: note: use -std=gnu++11 or -fext-numeric-literals to enable more built-in suffixes