#include<bits/stdc++.h>
using namespace std;
const int N=1e4+5;
int shi,n,a[N],b[N],sum=0;
int main(){
	scanf("%d%d",&shi,&n);
	for(int i=1;i<=n;i++){
		scanf("%d%d",&a[i],&b[i]);
		sort(a+1,a+n+1);
		sort(b+1,b+n+1);
		if(a[i]<=shi){
			sum+=b[i];
		}
	}cout<<sum;
    return 0;
}

rt