View Compilation Error

0_0_36652563_17410.c:9:6: error: variably modified 'ar' at file scope
 char ar[maxn];
      ^
0_0_36652563_17410.c: In function 'main':
0_0_36652563_17410.c:29:9: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
         for(ll i=0;i<cnt;i++){
         ^
0_0_36652563_17410.c:29:9: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code