为什么只有20分(Q A Q)-

#include<bits/stdc++.h>
using namespace std;
int n,a[11][11];
int vis[11][11];
int dx[5]={0,0,-1,1};
int dy[5]={-1,1,0,0};
int maxn=-1;
int sum=0,cnt=0;
int s1,s2;
void dfs(int x,int y){
	if(cnt>s1||cnt>s2)
		return;
	if(x==n&&y==n){
		maxn=max(maxn,sum);
		return;
	}
	for(int i=0;i<4;i++){
		int xx=x+dx[i];
		int yy=y+dy[i];
		if(xx>=1&&xx<=n&&yy>=1&&yy<=n&&vis[xx][yy]==0&&a[xx][yy]!=-1){
			vis[xx][yy]=1;
			sum+=a[xx][yy];
			cnt=a[xx][yy];
			dfs(xx,yy);
			vis[xx][yy]=0;
			sum-=a[xx][yy];
			cnt=0;
		}
	}
}
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		for(int j=1;j<=n;j++){
			char ch;
			cin>>ch;
			if(ch<='9'&&ch>='0')
				a[i][j]=ch-'0';
			else if(ch=='.')
				a[i][j]=0;
			else
				a[i][j]=-1;
		}
	}
	cin>>s1>>s2;
	dfs(1,1);
	if(maxn==-1)
		cout<<"Oh,dead...Well,that's great.";
	else
		cout<<maxn;
	return 0;
}