#include <iostream>
#include <vector>
int fastest[50][301];
struct SYM{int S;int Y;int M;};
std::vector<SYM> in[50];
int main(){
	int N,C,V;
	std::cin>>N>>C>>V;
	while(V--){
		SYM sym;int T;std::cin>>sym.S>>T>>sym.Y>>sym.M;
		sym.S--;
		in[T-1].push_back(sym);
	}
	for (int i=0;i<N;i++) {
		for (int j=0;j<=C;j++) {
			fastest[i][j]=200000;
		}
	}
	fastest[0][C]=0;
	for (int i = 1; i < N; i++) {
		for(auto e:in[i]){
			for(int j=0;j+e.Y<=C;j++)
				if(fastest[i][j+e.Y]>fastest[e.S][j]+e.M)fastest[i][j+e.Y]=fastest[e.S][j]+e.M;
		}
	}
	int min=200000;
	for(auto m:fastest[N-1])if(min>m)min=m;
	std::cout<<(min==200000?-1:min);
}