#include <stdio.h>

int naive(int N, int M, int ans[][501], int k)
{
	int i, j;
	for (i = 1; i <= N; i++) {
		for (j = 1; j <= M; j++) if (ans[i][j] == 0) break;
		if (j <= M) break;
	}
	if (i > N) return 1;
	
	if (i <= N - 2 && j <= M - 1) {
		if (ans[i][j] == 0 && ans[i][j+1] == 0 && ans[i+1][j] == 0 && ans[i+2][j] == 0) {
			ans[i][j] = k;
			ans[i][j+1] = k;
			ans[i+1][j] = k;
			ans[i+2][j] = k;
			if (naive(N, M, ans, k + 1) != 0) return 1;
			ans[i][j] = 0;
			ans[i][j+1] = 0;
			ans[i+1][j] = 0;
			ans[i+2][j] = 0;
		}
		if (ans[i][j] == 0 && ans[i][j+1] == 0 && ans[i+1][j+1] == 0 && ans[i+2][j+1] == 0) {
			ans[i][j] = k;
			ans[i][j+1] = k;
			ans[i+1][j+1] = k;
			ans[i+2][j+1] = k;
			if (naive(N, M, ans, k + 1) != 0) return 1;
			ans[i][j] = 0;
			ans[i][j+1] = 0;
			ans[i+1][j+1] = 0;
			ans[i+2][j+1] = 0;
		}
		if (ans[i][j] == 0 && ans[i+1][j] == 0 && ans[i+2][j] == 0 && ans[i+2][j+1] == 0) {
			ans[i][j] = k;
			ans[i+1][j] = k;
			ans[i+2][j] = k;
			ans[i+2][j+1] = k;
			if (naive(N, M, ans, k + 1) != 0) return 1;
			ans[i][j] = 0;
			ans[i+1][j] = 0;
			ans[i+2][j] = 0;
			ans[i+2][j+1] = 0;
		}
	}
	if (i <= N - 2 && j >= 2) {
		if (ans[i][j] == 0 && ans[i+1][j] == 0 && ans[i+2][j] == 0 && ans[i+2][j-1] == 0) {
			ans[i][j] = k;
			ans[i+1][j] = k;
			ans[i+2][j] = k;
			ans[i+2][j-1] = k;
			if (naive(N, M, ans, k + 1) != 0) return 1;
			ans[i][j] = 0;
			ans[i+1][j] = 0;
			ans[i+2][j] = 0;
			ans[i+2][j-1] = 0;
		}
	}
	if (i <= N - 1 && j <= M - 2) {
		if (ans[i][j] == 0 && ans[i][j+1] == 0 && ans[i][j+2] == 0 && ans[i+1][j] == 0) {
			ans[i][j] = k;
			ans[i][j+1] = k;
			ans[i][j+2] = k;
			ans[i+1][j] = k;
			if (naive(N, M, ans, k + 1) != 0) return 1;
			ans[i][j] = 0;
			ans[i][j+1] = 0;
			ans[i][j+2] = 0;
			ans[i+1][j] = 0;
		}
		if (ans[i][j] == 0 && ans[i][j+1] == 0 && ans[i][j+2] == 0 && ans[i+1][j+2] == 0) {
			ans[i][j] = k;
			ans[i][j+1] = k;
			ans[i][j+2] = k;
			ans[i+1][j+2] = k;
			if (naive(N, M, ans, k + 1) != 0) return 1;
			ans[i][j] = 0;
			ans[i][j+1] = 0;
			ans[i][j+2] = 0;
			ans[i+1][j+2] = 0;
		}
		if (ans[i][j] == 0 && ans[i+1][j] == 0 && ans[i+1][j+1] == 0 && ans[i+1][j+2] == 0) {
			ans[i][j] = k;
			ans[i+1][j] = k;
			ans[i+1][j+1] = k;
			ans[i+1][j+2] = k;
			if (naive(N, M, ans, k + 1) != 0) return 1;
			ans[i][j] = 0;
			ans[i+1][j] = 0;
			ans[i+1][j+1] = 0;
			ans[i+1][j+2] = 0;
		}
	}
	if (i <= N - 1 && j >= 3) {
		if (ans[i][j] == 0 && ans[i+1][j] == 0 && ans[i+1][j-1] == 0 && ans[i+1][j-2] == 0) {
			ans[i][j] = k;
			ans[i+1][j] = k;
			ans[i+1][j-1] = k;
			ans[i+1][j-2] = k;
			if (naive(N, M, ans, k + 1) != 0) return 1;
			ans[i][j] = 0;
			ans[i+1][j] = 0;
			ans[i+1][j-1] = 0;
			ans[i+1][j-2] = 0;
		}
	}
	return 0;
}

int solve(int N, int M, int ans[][501])
{
	if (N * M % 4 != 0 || N == 1 || M == 1 || (N % 4 == 2 && M % 4 == 2) || (N % 8 == 4 && M % 2 == 1) || (N % 2 == 1 && M % 8 == 4)) return 0;
	
	int i, j, k = 1;
	if (N % 4 == 0 && M % 2 == 0) {
		for (i = 1; i <= N; i += 4) {
			for (j = 1; j <= M; j += 2) {
				ans[i][j] = k;
				ans[i][j+1] = k;
				ans[i+1][j] = k;
				ans[i+1][j+1] = k + 1;
				ans[i+2][j] = k;
				ans[i+2][j+1] = k + 1;
				ans[i+3][j] = k + 1;
				ans[i+3][j+1] = k + 1;
				k += 2;
			}
		}
	} else if (N % 2 == 0 && M % 4 == 0) {
		for (i = 1; i <= N; i += 2) {
			for (j = 1; j <= M; j += 4) {
				ans[i][j] = k;
				ans[i][j+1] = k;
				ans[i][j+2] = k;
				ans[i][j+3] = k + 1;
				ans[i+1][j] = k;
				ans[i+1][j+1] = k + 1;
				ans[i+1][j+2] = k + 1;
				ans[i+1][j+3] = k + 1;
				k += 2;
			}
		}
	} else if (N % 8 == 0) {
		for (i = 1; i <= N; i += 8) {
			ans[i][1] = k;
			ans[i][2] = k;
			ans[i][3] = k;
			ans[i+1][1] = k;
			ans[i+1][2] = k + 1;
			ans[i+1][3] = k + 1;
			ans[i+2][1] = k + 2;
			ans[i+2][2] = k + 2;
			ans[i+2][3] = k + 1;
			ans[i+3][1] = k + 2;
			ans[i+3][2] = k + 3;
			ans[i+3][3] = k + 1;
			ans[i+4][1] = k + 2;
			ans[i+4][2] = k + 3;
			ans[i+4][3] = k + 4;
			ans[i+5][1] = k + 3;
			ans[i+5][2] = k + 3;
			ans[i+5][3] = k + 4;
			ans[i+6][1] = k + 5;
			ans[i+6][2] = k + 4;
			ans[i+6][3] = k + 4;
			ans[i+7][1] = k + 5;
			ans[i+7][2] = k + 5;
			ans[i+7][3] = k + 5;
			k += 6;
			for (j = 4; j <= M; j += 2) {
				ans[i][j] = k;
				ans[i][j+1] = k;
				ans[i+1][j] = k;
				ans[i+1][j+1] = k + 1;
				ans[i+2][j] = k;
				ans[i+2][j+1] = k + 1;
				ans[i+3][j] = k + 1;
				ans[i+3][j+1] = k + 1;
				ans[i+4][j] = k + 2;
				ans[i+4][j+1] = k + 2;
				ans[i+5][j] = k + 2;
				ans[i+5][j+1] = k + 3;
				ans[i+6][j] = k + 2;
				ans[i+6][j+1] = k + 3;
				ans[i+7][j] = k + 3;
				ans[i+7][j+1] = k + 3;
				k += 4;
			}
		}
	} else {
		static int _ans[501][501];
		for (i = 1; i <= M; i += 8) {
			_ans[i][1] = k;
			_ans[i][2] = k;
			_ans[i][3] = k;
			_ans[i+1][1] = k;
			_ans[i+1][2] = k + 1;
			_ans[i+1][3] = k + 1;
			_ans[i+2][1] = k + 2;
			_ans[i+2][2] = k + 2;
			_ans[i+2][3] = k + 1;
			_ans[i+3][1] = k + 2;
			_ans[i+3][2] = k + 3;
			_ans[i+3][3] = k + 1;
			_ans[i+4][1] = k + 2;
			_ans[i+4][2] = k + 3;
			_ans[i+4][3] = k + 4;
			_ans[i+5][1] = k + 3;
			_ans[i+5][2] = k + 3;
			_ans[i+5][3] = k + 4;
			_ans[i+6][1] = k + 5;
			_ans[i+6][2] = k + 4;
			_ans[i+6][3] = k + 4;
			_ans[i+7][1] = k + 5;
			_ans[i+7][2] = k + 5;
			_ans[i+7][3] = k + 5;
			k += 6;
			for (j = 4; j <= N; j += 2) {
				_ans[i][j] = k;
				_ans[i][j+1] = k;
				_ans[i+1][j] = k;
				_ans[i+1][j+1] = k + 1;
				_ans[i+2][j] = k;
				_ans[i+2][j+1] = k + 1;
				_ans[i+3][j] = k + 1;
				_ans[i+3][j+1] = k + 1;
				_ans[i+4][j] = k + 2;
				_ans[i+4][j+1] = k + 2;
				_ans[i+5][j] = k + 2;
				_ans[i+5][j+1] = k + 3;
				_ans[i+6][j] = k + 2;
				_ans[i+6][j+1] = k + 3;
				_ans[i+7][j] = k + 3;
				_ans[i+7][j+1] = k + 3;
				k += 4;
			}
		}
		for (i = 1; i <= N; i++) for (j = 1; j <= M; j++) ans[i][j] = _ans[j][i];
	}
	return 1;
}

int main()
{
	int T, N, M, ans[501][501] = {}, i, j;
	scanf("%d", &T);
	while (T--) {
		scanf("%d %d", &N, &M);
		if (solve(N, M, ans) == 0) printf("-1\n");
		else {
			printf("%d\n", N * M / 4);
			for (i = 1; i <= N; i++) {
				for (j = 1; j <= M; j++) printf("%d ", ans[i][j]);
				printf("\n");
			}
		}
	}
	fflush(stdout);
	return 0;
}