View Compilation Error

0_0_13944076_18764.c: In function 'fa':
0_0_13944076_18764.c:6:5: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
     for(int i = 1; i <= n; i++){
     ^
0_0_13944076_18764.c:6:5: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_13944076_18764.c: In function 'main':
0_0_13944076_18764.c:32:5: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
     for (int i = 0; i < 2*n; i++){
     ^
0_0_13944076_18764.c:35:14: error: redefinition of 'i'
     for (int i = 0; i < 2*n; i = i + 2){
              ^
0_0_13944076_18764.c:32:14: note: previous definition of 'i' was here
     for (int i = 0; i < 2*n; i++){
              ^
0_0_13944076_18764.c:35:5: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
     for (int i = 0; i < 2*n; i = i + 2){
     ^