View Compilation Error

0_0_19064947_30723.cpp: In function 'bool spfa(int, int)':
0_0_19064947_30723.cpp:44:5: error: 'queue' was not declared in this scope
     queue<int>q;
     ^
0_0_19064947_30723.cpp:44:11: error: expected primary-expression before 'int'
     queue<int>q;
           ^
0_0_19064947_30723.cpp:53:5: error: 'q' was not declared in this scope
     q.push(s);
     ^