新人求助，玄学95分，#WA13 ？？？

#include<queue>
#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#define rint register int 
#define inf 200000000
using namespace std;

const int maxn=125086;
const int maxm=2000086;

int head[maxn],to[maxm],Next[maxm],w[maxm];
int n,m,s,t,cnt=-1,dep[maxn],cur[maxn],p,d;
int v[48][48][48],num[48][48][48],Num,g1[6]={0,0,1,-1},g2[6]={1,-1,0,0};

inline int Read(){
    int x=0;char c=getchar();
    while (!isdigit(c))c=getchar();
    while (isdigit(c)){x=(x<<3)+(x<<1)+(c^48);c=getchar();}
    return x;
}

inline void add(int x,int y,int z){
    to[++cnt]=y,Next[cnt]=head[x],head[x]=cnt,w[cnt]=z;
    to[++cnt]=x,Next[cnt]=head[y],head[y]=cnt,w[cnt]=0;
}

inline int bfs(){
    memset(dep,0,sizeof(dep));
    queue<int> q;q.push(s);dep[s]=1;
    while (!q.empty()){
        int u=q.front();q.pop();
        for (rint i=head[u];i!=-1;i=Next[i]){
            int v=to[i];
            if (!dep[v] && w[i]>0){
                dep[v]=dep[u]+1;
                q.push(v);
            }
        }
    }
    return dep[t];
}

inline int dfs(int x,int dist){
    if (x==t)return dist;
    for (rint &i=cur[x];i!=-1;i=Next[i]){
        int v=to[i];
        if (w[i]>0 && dep[v]==dep[x]+1){
            int d=dfs(v,min(w[i],dist));
            if (d){
                w[i]-=d;
                w[i^1]+=d;
                return d;
            }
        }
    }
    return 0;
}

inline int dinic(){
    int ans=0;
    while (bfs()){
        for (rint i=s;i<=t;++i)cur[i]=head[i];
        while (int dd=dfs(s,inf))ans+=dd;
    }
    return ans;
}

int main(){
    memset(head,-1,sizeof(head));;cnt=-1;
    n=Read(),m=Read(),p=Read(),d=Read();
    s=0,t=(n*m)*(p+1)+1;
    for (rint z=1;z<=p;++z)
        for (rint x=1;x<=n;++x)
            for (rint y=1;y<=m;++y)
                v[x][y][z]=Read(),num[x][y][z]=++Num;
    for (rint i=1;i<=n;++i)for (rint j=1;j<=m;++j)num[i][j][0]=++Num;
    for (rint x=1;x<=n;++x){
        for (rint y=1;y<=m;++y){
            add(s,num[x][y][0],inf);
            add(num[x][y][p],t,inf);
            for (rint z=1;z<=p;++z){
                add(num[x][y][z-1],num[x][y][z],v[x][y][z]);
                if (z-d){
                    for (rint i=0;i<4;++i){
                        int xx=x+g1[i],yy=y+g2[i];
                        if (xx>=1 && xx<=n && yy>=1 && yy<=m){
                            add(num[x][y][z],num[xx][yy][z-d],inf);
                        }
                    }
                }
            }
        }
    }
    //printf("%d %d %d\n",s,t,Num);
    printf("%d",dinic());
    return 0;
}