View Compilation Error

0_0_17768735_25995.c:3:5: error: variably modified 'F' at file scope
 int F[MAXN];
     ^
0_0_17768735_25995.c: In function 'main':
0_0_17768735_25995.c:22:9: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
         for(int i=1;i<=n;i++) F[i]=-1;
         ^
0_0_17768735_25995.c:22:9: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_17768735_25995.c:30:17: error: redefinition of 'i'
         for(int i=1;i<=n;i++)
                 ^
0_0_17768735_25995.c:22:17: note: previous definition of 'i' was here
         for(int i=1;i<=n;i++) F[i]=-1;
                 ^
0_0_17768735_25995.c:30:9: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
         for(int i=1;i<=n;i++)
         ^