/in/foo.cc: In function 'void ins(int)':
/in/foo.cc:17:20: error: 'k' was not declared in this scope
 void ins(int x){x%=k;num[x]++; nowans+=num[x]-1;}
                    ^
/in/foo.cc: In function 'void del(int)':
/in/foo.cc:18:20: error: 'k' was not declared in this scope
 void del(int x){x%=k;num[x]--; nowans-=num[x];} 
                    ^