View Compilation Error

0_0_9452278_23669.cpp: In function `void BFS(int)':
0_0_9452278_23669.cpp:20: error: `queue' undeclared (first use this function)
0_0_9452278_23669.cpp:20: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_9452278_23669.cpp:20: error: expected primary-expression before "int"
0_0_9452278_23669.cpp:20: error: expected `;' before "int"
0_0_9452278_23669.cpp:24: error: `q' undeclared (first use this function)