View Compilation Error

0_0_24845087_11982.c:7:5: error: variably modified 'next' at file scope
 int next[maxn];
     ^
0_0_24845087_11982.c:8:6: error: variably modified 'a' at file scope
 char a[maxn];
      ^
0_0_24845087_11982.c: In function 'main':
0_0_24845087_11982.c:41:9: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
         for(int i=2;i<=n;i++)
         ^
0_0_24845087_11982.c:41:9: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code