#include<bits/stdc++.h>
using namespace std;
const int MAXN=105;
int dp[MAXN][3];
int main()
{
int n;
cin>>n;
cin>>dp[0][0]>>dp[0][1]>>dp[0][2];
for(int i=1;i<n;i++)
{
int r,b,g;
cin>>r>>b>>g;
dp[i][0]=min(dp[i-1][1],dp[i-1][2])+r;
dp[i][1]=min(dp[i-1][0],dp[i-1][2])+b;
dp[i][2]=min(dp[i-1][0],dp[i-1][1])+g;
}
int ans=min(dp[n-1][0],min(dp[n-1][1],dp[n-1][2]));
cout<<ans<<"\n";
return 0;
}