View Compilation Error

0_0_2987568_15534.c: In function `main':
0_0_2987568_15534.c:10: error: `flag' undeclared (first use in this function)
0_0_2987568_15534.c:10: error: (Each undeclared identifier is reported only once
0_0_2987568_15534.c:10: error: for each function it appears in.)
0_0_2987568_15534.c:10: error: `false' undeclared (first use in this function)