分支语句 + 初中数学（平面直角坐标系）

#include<bits/stdc++.h>
using namespace std;
int main(){
    int x,y;
    cin>>x>>y;
    if(x==1 and y==-1) cout<<"yes";
    else if(x==1 and y==1) cout<<"yes";
    else if(x==-1 and y==-1) cout<<"yes";
    else if(x==-1 and y==1) cout<<"yes";
    else if(x==0 and y==0) cout<<"yes";
    else cout<<"no";
    return 0;
}