BOJ-1149

#include <iostream>
#include <algorithm>

using namespace std;

#define MAX 1000
int house[MAX][3];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(NULL); cout.tie(NULL);

    int N;
    cin >> N;
    int cost[3];

    if (N<1 || N>1000) return 0;
    
    for (int i=0; i<N; i++) {
        cin >> cost[0] >> cost[1] >> cost[2];
        house[i+1][0] = min(house[i][1],house[i][2])+cost[0];
        house[i+1][1] = min(house[i][0],house[i][2])+cost[1];
        house[i+1][2] = min(house[i][1],house[i][0])+cost[2];
    }
    
    cout << min(house[N][2],min(house[N][0],house[N][1]));
}