View Compilation Error

0_0_18908212_11244.c: In function 'main':
0_0_18908212_11244.c:22:8: error: unknown type name 'bool'
        bool mark = 0;
        ^
0_0_18908212_11244.c:28:45: error: lvalue required as left operand of assignment
               (mark) ? printf ("\n") : mark = 1;
                                             ^