#define MD 998244353
#define U(X) b=t||A*k%K<1,((t+=A*k%K)<K||(t-=K)<1)&&b?a:a+=X
ll@N,@A,@K,L=2K,R=N%L+1,t=0,b;Mint Q=N/L,a=sum[k,R,R+L](((A*L*(2Q-1)/3+(A*k/K*K+A*k))*(Q-1)+A*k/K*k)*2Q);rrep(k,R,R+L)U((K*(Q-1)+k)*2Q);t=0;rrep(k,R)U(2k);wt(a+sum[k,1,R](A*k/K*2*k));