#include<bits/stdc++.h>
using namespace std;
int t, n, m, dp[1505][1105];
struct node { int tim, pic; }tr[10005];
inline int read()
{
    int red = 0, f_f = 1; char ch = getchar();
    while(ch>'9' || ch <'0') {if(ch=='-') f_f = -1;	ch = getchar();}
    while(ch>='0' &&ch<='9') red = red*10+ch-'0', ch = getchar();
    return red*f_f;
}
void dfs_read(int a)
{
    tr[a].tim = read() * 2, tr[a].pic = read();
    if(!tr[a].pic) dfs_read(a << 1), dfs_read(a << 1| 1);
}
void dfs(int a, int r)
{
    if(dp[a][r] || !r) return;
    if(tr[a].pic) { dp[a][r] = min(tr[a].pic, (r - tr[a].tim) / 5); return; }
    for (int i = 0; i <= r - tr[a].tim; i++) dfs(a << 1, i), dfs(a << 1 | 1, r - tr[a].tim - i), dp[a][r] = max(dp[a][r], dp[a << 1][i] + dp[a << 1 | 1][r - tr[a].tim - i]);
}
int main()
{
    memset(dp, 0, sizeof(dp));
    t = read() - 1, dfs_read(1), dfs(1, t), printf("%d", dp[1][t]);
    return 0;
}