View Compilation Error

0_0_7595481_7826.c:3: error: syntax error before "change"
0_0_7595481_7826.c: In function `change':
0_0_7595481_7826.c:6: error: `bool' undeclared (first use in this function)
0_0_7595481_7826.c:6: error: (Each undeclared identifier is reported only once
0_0_7595481_7826.c:6: error: for each function it appears in.)
0_0_7595481_7826.c:6: error: syntax error before "flag"
0_0_7595481_7826.c:11: error: `true' undeclared (first use in this function)
0_0_7595481_7826.c:15: error: `flag' undeclared (first use in this function)
0_0_7595481_7826.c:20: error: `false' undeclared (first use in this function)
0_0_7595481_7826.c: In function `main':
0_0_7595481_7826.c:25: error: `bool' undeclared (first use in this function)
0_0_7595481_7826.c:25: error: syntax error before "flag"
0_0_7595481_7826.c:41: error: `flag' undeclared (first use in this function)