B.cpp

#include <algorithm>
#include <iostream>
#include <cstring>
#include <climits>
#include <cstdio>
#include <vector>
#include <cstdlib>
#include <ctime>
#include <cmath>
#include <queue>
#include <stack>
#include <map>
#include <set>

#define Re register
#define LL long long
#define U unsigned
#define FOR(i,a,b) for(Re int i = a;i <= b;++i)
#define RFOR(i,a,b) for(Re int i = a;i >= b;--i)
#define SFOR(i,a,b,c) for(Re int i = a;i <= b;i+=c)
#define CLR(i,a) memset(i,a,sizeof(i))
#define BR printf("--------------------\n")
#define DEBUG(x) std::cerr << #x << '=' << x << std::endl

namespace fastIO{ 
    #define BUF_SIZE 100000 
    #define OUT_SIZE 100000 
    #define ll long long 
    bool IOerror=0; 
    inline char nc(){ 
        static char buf[BUF_SIZE],*p1=buf+BUF_SIZE,*pend=buf+BUF_SIZE; 
        if (p1==pend){ 
            p1=buf; pend=buf+fread(buf,1,BUF_SIZE,stdin); 
            if (pend==p1){IOerror=1;return -1;} 
        } 
        return *p1++; 
    } 
    inline bool blank(char ch){return ch==' '||ch=='\n'||ch=='\r'||ch=='\t';} 
    inline void read(int &x){ 
        bool sign=0; char ch=nc(); x=0; 
        for (;blank(ch);ch=nc()); 
        if (IOerror)return; 
        if (ch=='-')sign=1,ch=nc(); 
        for (;ch>='0'&&ch<='9';ch=nc())x=x*10+ch-'0'; 
        if (sign)x=-x; 
    } 
    inline void read(ll &x){ 
        bool sign=0; char ch=nc(); x=0; 
        for (;blank(ch);ch=nc()); 
        if (IOerror)return; 
        if (ch=='-')sign=1,ch=nc(); 
        for (;ch>='0'&&ch<='9';ch=nc())x=x*10+ch-'0'; 
        if (sign)x=-x; 
    } 
    #undef ll 
    #undef OUT_SIZE 
    #undef BUF_SIZE 
}; 
using namespace fastIO;

struct Point{
    double x,y;
}p;

double cross(Point& p1, Point& p2,Point& p)
{
	return (p2.x - p1.x) * (p.y - p1.y) -(p.x - p1.x) * (p2.y - p1.y);
}


int N,D,M;
int main(){
    read(N);read(D);read(M);
    Point p1,p2,p3,p4;
    p1 = (Point){0,D};p2 = (Point){D,0};
    p3 = (Point){N,N-D};p4 = (Point){N-D,N};

    FOR(i,1,M){
        int x,y;read(x);read(y);
        p = (Point){x,y};
        if(cross(p1,p2,p) * cross(p3,p4,p) >= 0 && cross(p2,p3,p) * cross(p4,p1,p) >= 0) 
            puts("YES");
        else puts("NO");
    }
    return 0;
}