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#include <bits/stdc++.h>
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using namespace std;
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const int N = 1010;
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int a[N][N], f[N][N];
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int n;
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int main()
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{
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  cin >> n;
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  for (int i = 1; i <= n; i ++ )
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    for (int j = 1; j <= i; j ++ )
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      cin >> a[i][j];
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  for (int i = 1; i <= n; i ++ )  f[n][i] = w[n][i];
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    for (int i = n - 1; i > 0; i ++ )
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        for (int j = 1; j <= i; j ++ )
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            f[i][j] = max(f[i + 1][j], f[i + 1][j + 1]);
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    int res = -2e9;
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    for (int i = 1; i <= n; i ++ )  res = max(res, f[n][i]);
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    cout << res << endl;
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    return 0;
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}