View Compilation Error

0_0_36447062_9860.c: In function 'main':
0_0_36447062_9860.c:12:9: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
         for(int i=2; i*i<=(int)(n+1); i++)
         ^
0_0_36447062_9860.c:12:9: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code