震惊！刚学OI的萌新竟只拿了60分！

#include<iostream>
using namespace std;
int n,m,hx,hy;
unsigned long long map[25][25];
bool horse[25][25];

int main(){
    cin>>n>>m>>hx>>hy;
    for(int i = 0;i<=n;i++){
        map[i][0] = 1;
    }
    for(int i = 0;i<=m;i++){
        map[0][i] = 1;
    }
    horse[hx+1][hy+2] = 1;
    horse[hx+1][hy-2] = 1;
    horse[hx-1][hy+2] = 1;
    horse[hx-1][hy-2] = 1;
    horse[hx+2][hy+1] = 1;
    horse[hx+2][hy-1] = 1;
    horse[hx-2][hy+1] = 1;
    horse[hx-2][hy-1] = 1;
    horse[hx][hy] = 1;
    for(int i = 1;i<=n;i++){
        for(int j = 1;j<=m;j++){
            map[i][j] = !horse[i][j] * (map[i-1][j] * !horse[i-1][j] + map[i][j-1] * !horse[i][j-1]);
            //cout<<map[i][j]<<"\t";
        }
        //cout<<endl;
    }
    cout<<map[n][m];
    return 0;
}