View Compilation Error

0_0_21620519_5532.c: In function 'main':
0_0_21620519_5532.c:10:9: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
         for (int i=0;i<month-1;i++)
         ^
0_0_21620519_5532.c:10:9: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code