View Compilation Error

0_0_4010774_28818.c: In function `main':
0_0_4010774_28818.c:15: error: `bool' undeclared (first use in this function)
0_0_4010774_28818.c:15: error: (Each undeclared identifier is reported only once
0_0_4010774_28818.c:15: error: for each function it appears in.)
0_0_4010774_28818.c:15: error: syntax error before "flag"
0_0_4010774_28818.c:18: error: `flag' undeclared (first use in this function)
0_0_4010774_28818.c:68: error: invalid lvalue in assignment