View Compilation Error

0_0_13779789_20307.c:1:7: error: expected declaration specifiers or '...' before 'sizeof'
 alloc(sizeof(int)*1000);
       ^
0_0_13779789_20307.c:2:2: error: expected identifier or '(' before 'while'
  while(scanf("%d",&n)!=0)
  ^
0_0_13779789_20307.c:16:2: error: expected identifier or '(' before 'return'
  return 0;
  ^
0_0_13779789_20307.c:17:1: error: expected identifier or '(' before '}' token
 }
 ^