#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")

char*mmap();
#define rd_skip() while(*rp++>=48)
#define rd(v) int v=0;{int _c;while(_c=*rp++-48,_c>=0)v=v*10+_c;}

char wbuf[1<<27];

#define WTHI(v) {long _z=v,_n=0,_d=0;while(++_n,_d=_d<<8|0x30|_z%10,_z/=10);*(long*)wp=_d;wp+=_n;}

long numstrs[1024];
int numstrlens[1024];
void mknumstrs(){
	for(int i=0;i<1024;++i){
		long _z=i,n=0,_d=0;
		while(++n,_d=_d<<8|0x30|_z%10,_z/=10);
		numstrs[i]=_d<<8|0x20;
		numstrlens[i]=n+1;
	}
}
#define wt(v) (*(long*)wp=numstrs[v],wp+=numstrlens[v])

main(){
	mknumstrs();

	char*rp=mmap(0l,1l<<28,1,2,0,0ll);
	char*wp=wbuf;

	rd_skip();
	while(*rp){
		rd(n);
		rd(m);
		if(n==1&&m==1){
			*(long*)wp=*(long*)" 0 1 1";
			wp+=6;
			continue;
		}
		if((n|m)&1){
			*(long*)wp=*(long*)" -1";
			wp+=3;
			continue;
		}
		*wp++=32;
		WTHI(m*n-1);
		for(int y=0;y<n;y+=2){
			if(!(y&2)){
				for(int x=0;x<m-2;x+=2){
					wt(y+1); wt(x+1);
					wt(y+2); wt(x+2);
					wt(y+2); wt(x+1);
					wt(y+1); wt(x+2);
				}
				{
					wt(y+1); wt(m-1);
					wt(y+2); wt(m-0);
					wt(y+1); wt(m-0);
					wt(y+2); wt(m-1);
				}
			}else{
				{
					wt(y+1); wt(m-1);
					wt(y+2); wt(m-0);
					wt(y+1); wt(m-0);
					wt(y+2); wt(m-1);
				}
				for(int x=m-2;x-=2,x>=0;){
					wt(y+2); wt(x+2);
					wt(y+1); wt(x+1);
					wt(y+1); wt(x+2);
					wt(y+2); wt(x+1);
				}
			}
		}
	}

	write(1,wbuf,wp-wbuf);
	_exit(0);
}