View Compilation Error

0_0_24651654_137.c: In function 'main':
0_0_24651654_137.c:5:2: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
  for (long long int i = 1; i < 16; i++)
  ^
0_0_24651654_137.c:5:2: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_24651654_137.c:8:3: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
   for (long long int j = 1; j <= i; j++){
   ^
0_0_24651654_137.c:11:3: error: expected expression before '/' token
   //    printf("%lld\n",a[i]);
   ^
0_0_24651654_137.c:17:3: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
   for (int i = 1; i < 16; i++)
   ^