legendre-steveverrill.c

a,b,c,d,m=1,n,q,r;main(){for(scanf("%d",&n);n%4<1;n/=4)m*=2;for(a=sqrt(n),n-=a*a,a-=(3+n)%4/2;r=n-b*b-c*c,d=sqrt(r),d*d-r;c=q%256)b=++q>>8;printf("%d %d %d %d",a*m,b*m,c*m,d*m);}