为什么全RE

#include<bits/stdc++.h>
#define int long long
using namespace std;
struct coord{
    int xx, yy;
};
queue<coord> q;
int ans[410][410];
int dir[8][2] = {
    2, 1,
    1, 2,
    -1, 2,
    -2, 1,
    -2, -1,
    -1, -2,
    1, -2,
    2, -1
};
int n, m, x, y;
signed main(){
    cin >> n >> m >> x >> y;
    memset(ans, -1, sizeof(ans));
    coord tmp = {x, y};
    q.push(tmp);
    ans[x][y] = 0;
    while(!q.empty()){
        coord u = q.front();
        int ux = u.xx, uy = u.yy;
        q.pop();
        for(int i = 0;i < 8;i++){
            int sx = ux + dir[i][0], sy = uy + dir[i][1];
            int b = ans[ux][uy];
            if(x < 1 || x > n || y < 1 || y > m || ans[sx][sy] != -1) continue;
            ans[sx][sy] = b + 1;
            coord tmp = {sx, sy};
            q.push(tmp);
        }
    }
    for(int i = 1;i <= n;i++){
        for(int j = 1;j <= m;j++){
            printf("%-5d", ans[i][j]);
        }
        printf("\n");
    }

    return 0;
}