#include<iostream>#include<cstdio>#include<cstring>#include<string>#include<cmath>#include<cstdlib>#include<algorithm>#include<queue>#include<vector>using namespace std;int main(){    int n,m,a,b;    scanf("%d%d",&n,&m);    long long now,w[m+1][n+1],f[m+1][n+1];    memset(w,0,sizeof(w));    memset(f,0,sizeof(f));    for(int i=1;i<=m;i++){        scanf("%d%d",&a,&b);        for(int j=1;j<=n;j++){            now=j;            for(int k=2;k<=b;k++) now*=j;            now*=a;            w[i][j]=now;            if(i==1) f[i][j]=w[i][j];            else f[i][j]=499999999;        }    }    for(int i=2;i<=m;i++)      for(int j=1;j<=n;j++)        for(int k=0;k<=j;k++)          if(f[i][j]>f[i-1][k]+w[i][j-k])            f[i][j]=f[i-1][k]+w[i][j-k];    printf("%lld\n",f[m][n]);    return 0;}