View Compilation Error

134995_0_20945.c: In function `main':
134995_0_20945.c:6: error: `i' undeclared (first use in this function)
134995_0_20945.c:6: error: (Each undeclared identifier is reported only once
134995_0_20945.c:6: error: for each function it appears in.)
134995_0_20945.c: In function `f':
134995_0_20945.c:18: error: `z' undeclared (first use in this function)