代码:

#include<iostream>
using namespace std;
const int N = 1010;
bool vis[N][N];
int t;
int n , m , ans;
int fx[] = {0 , 1 , 0};
int fy[] = {0 , 0 , 1};
void dfs(int x , int y){
	if(x == n && y == m){
		ans++;
		return ;
	}
	for(int i = 1;i <= 2;i++){
		int newx = x + fx[i];
		int newy = y + fy[i];
		if(newx >= 1 && newx <= n && newy >= 1 && newy <= m && !vis[newx][newy]){
			vis[newx][newy] = 1;
			dfs(newx , newy);
			vis[newx][newy] = 0;	
		}
	}
}
int main(){
	cin >> n >> m;
	cin >> t;
	for(int i = 1;i <= t;i++){
		int x , y;
		cin >> x >> y;
		vis[x][y] = true;
	}
	dfs(1 , 1);
	cout << ans << endl;
	return 0;
}

交了之后会弹出

UnexpectedResponse: got an unexpected response when requesting `https://atcoder.jp/login`: unable to find the csrf token

这咋回事？？