View Compilation Error

0_0_21139935_21569.cpp: In function 'int main()':
0_0_21139935_21569.cpp:56:26: error: unable to find numeric literal operator 'operator""nf'
               maps[i][j]=1nf; //初始为1表示i到j没有关系
                          ^
0_0_21139935_21569.cpp:56:26: note: use -std=gnu++11 or -fext-numeric-literals to enable more built-in suffixes