View Compilation Error

0_0_17152533_18167.c:4:1: error: unknown type name 'using'
 using namespace std;
 ^
0_0_17152533_18167.c:4:17: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'std'
 using namespace std;
                 ^
0_0_17152533_18167.c:20:5: error: variably modified 'ans' at file scope
 int ans[N<<2];
     ^
0_0_17152533_18167.c:21:6: error: variably modified 's' at file scope
 char s[N];
      ^