p27_lot3.cpp

#include<cstdio>
#include<algorithm>

int const N_MAX = 1000;

bool binary_search(int *k, int x){

	int l = 0, r = sizeof(k)/sizeof(*k);

	while( r-l > 1){
		int i = (r + l) /2;
		if( k[i] == x )
			return true;
		else if( k[i] < x )
			l = i + 1;
		else
			r = i;

	}
	return false;

}

int main(){

	int n, m, k[N_MAX], s[N_MAX*N_MAX];

	scanf("%d %d", &n, &m);

	for(int i=0; i<n; i++)
		scanf("%d", &k[i]);


	for(int i=0; i<n; i++){
		for(int j=0; j<n; j++){
			s[i*n+j] = k[i]+k[j];
		}
	}

	std::sort(s, s+n*n);

	for(int i=0; i<n; i++){
		for(int j=0; j<n; j++){
			if(binary_search(s, m-k[i]-k[j])){
				puts("Yes");
				return 0;
			}
		}
	}

	puts("No");
	return 0;
}