#include <cstdio>
using namespace std;

int index, i, j, M, N, matrix[1002][1002], arr[1000004];

int main(){

scanf("%d", &M);
scanf("%d", &N);

for(i = 0; i < M; i++){
    for(j = 0; j < N; j++){
        scanf("%d", &matrix[i][j]);
    }
}i = 0; j = 0;

for(index = 1; index <= M * N; index++){

    arr[index] = matrix[i][j];
    matrix[i][j] = 32769;

    if(j != (N - 1) && matrix[i][j+1] != 32769 && (!i || matrix[i-1][j] == 32769)) j++;
    else if(i != (M - 1) && matrix[i+1][j] != 32769) i++;
    else if(j && matrix[i][j-1] != 32769) j--;
    else if(i && matrix[i-1][j] != 32769) i--;
}

for(i = 1; i <= M * N; i++){
    printf("%d ", arr[i]);
}
return 0;
}