#include<bits/stdc++.h> using namespace std; const int maxn = 0x3f3f3f3f; int x[1001][1001]; int n,a,b,c; signed main(){ cin >> n; memset(x,maxn,sizeof(x)); cin >> a >> b >>c; x[a][b] = c; while(a!=0&&b!=0&&c!=0){ cin >> a >> b >>c; x[a][b] = c; } for(int i = 1;i <= n;i++){ for(int j = 1;j <= n;j++){ for(int k = 1;k <= n;k++){ x[i][j] = min(x[i][j],x[i][k]+x[k][j]); } } } cout << x[1][n]; return 0; }