View Compilation Error

0_0_35855136_441.c:6:1: error: expected identifier or '(' before '/' token
 //const int maxn = 1e6;
 ^
0_0_35855136_441.c:7:9: error: 'maxn' undeclared here (not in a function)
 char ss[maxn + 10];
         ^
0_0_35855136_441.c: In function 'Euler':
0_0_35855136_441.c:11:1: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
 for (long long i = 2; i <= sqrt(n); i++)
 ^
0_0_35855136_441.c:11:1: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_35855136_441.c: In function 'main':
0_0_35855136_441.c:48:1: error: expected expression before '/' token
 //printf("%lld\n",m);
 ^
0_0_35855136_441.c:51:1: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
 for (int i = 0; i < ind; i++)
 ^