C++ :

#include <bits/stdc++.h>
using namespace std;

int n,m;
int q[11000][3];
int a[110][110];
int i,j,head=1,tail=1;
int fx[5] = {0,0,1,0,-1};
int fy[5] = {0,1,0,-1,0};

int main(){
	cin>>n>>m;
	
	q[head][1] = 1;
	q[head][2] = 1;
	int tx,ty;
	a[1][1] = 1;
	int k = 2;
	while(head <= tail){
		for(i = 1;i <= 4;i++){
			tx = q[head][1] + fx[i];
			ty = q[head][2] + fy[i];
			if(tx >= 1 && tx <= n && ty >= 1 && ty <= m && a[tx][ty] == 0){
				tail++;
				q[tail][1] = tx;
				q[tail][2] = ty;
				a[tx][ty] = k;
				k++;
			}
		}
		head++;
	}
	
	for(i = 1;i <= n;i++){
		for(j = 1;j <= m;j++){
			cout<<a[i][j];
			if(j != m){
				cout<<" ";
			}
		}
		cout<<endl;
	}
	
	return 0;
}