import std.algorithm, std.container, std.conv, std.math, std.range, std.typecons, std.stdio, std.string;

auto rdsp(){return readln.splitter;}
void pick(R,T)(ref R r,ref T t){t=r.front.to!T;r.popFront;}
void readV(T...)(ref T t){auto r=rdsp;foreach(ref v;t)pick(r,v);}
void readA(T)(size_t n,ref T[]t){t=new T[](n);auto r=rdsp;foreach(ref v;t)pick(r,v);}
void readM(T)(size_t r,size_t c,ref T[][]t){t=new T[][](r);foreach(ref v;t)readA(c,v);}

void main()
{
  int n; readV(n);
  int[][] a; readM(n, 3, a);

  auto dp = new int[][](n, 3);
  dp[0] = a[0];

  foreach (i; 1..n)
    foreach (j; 0..3)
      foreach (k; 0..3)
        if (j != k)
          dp[i][j] = max(dp[i][j], dp[i-1][k] + a[i][j]);

  writeln(dp[$-1].reduce!max);
}
