View Compilation Error

0_0_3870270_19197.c:2:17: queue: No such file or directory
0_0_3870270_19197.c:3: error: syntax error before "namespace"
0_0_3870270_19197.c: In function `BFS':
0_0_3870270_19197.c:13: error: `queue' undeclared (first use in this function)
0_0_3870270_19197.c:13: error: (Each undeclared identifier is reported only once
0_0_3870270_19197.c:13: error: for each function it appears in.)
0_0_3870270_19197.c:13: error: syntax error before "int"
0_0_3870270_19197.c:14: error: `a' undeclared (first use in this function)