#include<bits/stdc++.h> using namespace std; struct A{ int time; int money; }; bool cmp(A B,A C){ return B.money>C.money; } int main(){ int t,m,k=0; cin>>t>>m; A all[m]; int all_money=0,all_time; for(int i=0;i<m;i++){ cin>>all[i].time>>all[i].money; } sort(all,all+m,cmp); while(1){ all_money+=all[k].money; t-=all[k].time; if(t<=0) break; k++; } all_money-=all[k].money; cout<<all_money; return 0; }