View Compilation Error

0_0_27099796_8166.c: In function 'JC':
0_0_27099796_8166.c:4:2: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
  for (int i = 2; i <= n; i++) {
  ^
0_0_27099796_8166.c:4:2: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_27099796_8166.c: In function 'main':
0_0_27099796_8166.c:13:2: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
  for (int i = 2; i < 20; i++) {
  ^
0_0_27099796_8166.c:16:11: error: redefinition of 'i'
  for (int i = 0; i < C; i++) {
           ^
0_0_27099796_8166.c:13:11: note: previous definition of 'i' was here
  for (int i = 2; i < 20; i++) {
           ^
0_0_27099796_8166.c:16:2: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
  for (int i = 0; i < C; i++) {
  ^