View Compilation Error

0_0_1541125_8903.c: In function `main':
0_0_1541125_8903.c:12: error: `z' undeclared (first use in this function)
0_0_1541125_8903.c:12: error: (Each undeclared identifier is reported only once
0_0_1541125_8903.c:12: error: for each function it appears in.)
0_0_1541125_8903.c:12: error: `false' undeclared (first use in this function)