#include<cstdio>

 #include<cstdlib>

 #include<cmath>

 #include<cstring>

 #include<algorithm>

 #include<iostream>

 #include<vector>

 #include<map>

 #include<set>

 #include<queue>

 #include<string>

 #define inf 1000000000

 #define maxn 100000+5

 #define maxm 100000+5

 #define eps 1e-10

 #define ll long long

 #define pa pair<int,int>

 #define for0(i,n) for(int i=0;i<=(n);i++)

 #define for1(i,n) for(int i=1;i<=(n);i++)

 #define for2(i,x,y) for(int i=(x);i<=(y);i++)

 #define for3(i,x,y) for(int i=(x);i>=(y);i--)

 #define for4(i,x) for(int i=head[x],y=e[i].go;i;i=e[i].next,y=e[i].go)

 #define mod 1000000007

 using namespace std;

 inline int read()

 {

     int x=,f=;char ch=getchar();

     while(ch<''||ch>''){if(ch=='-')f=-;ch=getchar();}

     while(ch>=''&&ch<=''){x=*x+ch-'';ch=getchar();}

     return x*f;

 }

 int n,mx,a[],b[],bin[],s[maxn],t[maxn],f[maxn];

 int main()

 {

     freopen("input.txt","r",stdin);

     freopen("output.txt","w",stdout);

     mx=read();n=read();

     for1(i,n)a[i]=read(),b[i]=read();

     bin[]=;

     for1(i,n)bin[i]=bin[i-]<<;

     for1(i,bin[n]-)for1(j,n)if(i&bin[j-])t[i]=max(t[i],a[j]),s[i]+=b[j];

     memset(f,,sizeof(f));

     f[]=;

     for1(i,bin[n]-)

      for(int j=i;j;j=i&(j-))

       if(s[j]<=mx)f[i]=min(f[i],t[j]+f[i^j]);

     cout<<f[bin[n]-]<<endl;

     return ;

 }