View Compilation Error

106465_0_9496.c: In function `main':
106465_0_9496.c:9: error: `a' undeclared (first use in this function)
106465_0_9496.c:9: error: (Each undeclared identifier is reported only once
106465_0_9496.c:9: error: for each function it appears in.)
106465_0_9496.c:9: error: syntax error before "scanf"