#include<iostream>
#include<cstring>
using namespace std;
int n=1;
int a[201][73],l[201],r[201],b[201],c[201];
void buildtree(int x,int lr)
{
    n++;
    cin>>b[n]>>c[n];
    if(lr==1)l[x]=n;else r[x]=n;
    int n1=n;
    if(c[n]==0)
    {
        buildtree(n1,1);
        buildtree(n1,2);
    }
}
void dfs(int i)
{
    if(l[i]==0&&r[i]==0)
    {
        a[i][0]=0;
        for(int j=1;j<=c[i];j++)
            a[i][j]=5*j+b[i]*2;
    }
    else
    {
        dfs(l[i]);
        dfs(r[i]);
        for(int j=0;j<=72;j++)
            for(int k=0;k<=72-j;k++)
                if(a[i][j+k]>a[l[i]][j]+a[r[i]][k]+b[i]*2)
                    a[i][j+k]=a[l[i]][j]+a[r[i]][k]+b[i]*2;
    }
}
int main()
{
    int t;
    cin>>t;
    buildtree(1,1);
    memset(a,2e9,sizeof(a));
    dfs(2);
    int i=72;
    while(a[2][i]>t)i--;
    cout<<i;
    return 0;
}