以下是他的代码：

#include<bits/stdc++.h>
#define reg register

const int maxn = 105;

int M;
int N;
int K;
int Ans;
int mark[maxn];
int Min_cost[maxn];
int Max_t[maxn][maxn];

bool Used[maxn];
bool like[maxn][maxn];

struct Node{ int x, y; } A[maxn], B[maxn];

bool Pd(Node zd, Node wq){
        int t1 = zd.x-wq.x, t2 = zd.y-wq.y;
        return t1*t1 + t2*t2 <= K*K;
}

bool Find(int x){
        for(reg int i = 1; i <= N; i ++)
                if(like[i][x] && !Used[i]){
                        Used[i] = 1;
                        if(!mark[i] || Find(mark[i])){ mark[i] = x; return 1; }
                }
        return 0;
}

void DFS(int k, int cnt){
        if(cnt + Min_cost[k] >= Ans) return ;
        if(k == M+1){ Ans = std::min(Ans, cnt); return ; }
        int Tmp_1[maxn];
        for(reg int i = k; i <= M; i ++){
// memcpy(Tmp_1, mark, sizeof Tmp_1);
                for(reg int j = 1; j <= N; j ++){
                        Tmp_1[j] = mark[j];
                        if(Max_t[j][k] >= i) like[j][cnt+1] = 1; 
                }
                
                memset(Used, 0, sizeof Used);
                if(Find(cnt+1)) DFS(i+1, cnt+1);

                for(reg int j = 1; j <= N; j ++){
                	mark[j] = Tmp_1[j];
                        if(Max_t[j][k] >= i) like[j][cnt+1] = 0;
                }
// memcpy(mark, Tmp_1, sizeof mark);
        }
}

int main(){
        scanf("%d%d%d", &M, &N, &K);
        for(reg int i = 1; i <= M; i ++) scanf("%d%d", &A[i].x, &A[i].y);
        for(reg int i = 1; i <= N; i ++) scanf("%d%d", &B[i].x, &B[i].y);
        for(reg int i = 1; i <= N; i ++)
                for(reg int j = M; j >= 1; j --)
                        if(Pd(B[i], A[j])) Max_t[i][j] = std::max(Max_t[i][j+1], j);
        memset(Min_cost, 0x3f, sizeof Min_cost);
        Min_cost[M+1] = 0;
        for(reg int i = M; i >= 1; i --)
                for(reg int j = 1; j <= N; j ++)
                        if(Pd(B[j], A[i]))
                                Min_cost[i] = std::min(Min_cost[i], Min_cost[Max_t[j][i] + 1] + 1);
        Ans = N;
        DFS(1, 0);
        printf("%d\n", Ans);
        return 0;
}