#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;
typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;
typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;
#define FOR(i, a, b) for (int i=a; i<(b); i++)
#define F0R(i, a) for (int i=0; i<(a); i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)
#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()
const int MOD = 1000000007;
const ll INF = 1e18;
const int MX = 100001;
int n,m, cur[MX];
vi radj[MX];
priority_queue<int> p[MX];
set<pi> nex;
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n >> m;
F0R(i,m) {
int a,b,c; cin >> a >> b >> c;
p[a].push(c);
radj[b].pb(a);
}
FOR(i,1,n+1) cur[i] = MOD;
cur[n] = 0;
FOR(i,1,n+1) nex.insert({cur[i],i});
while (sz(nex)) {
auto a = *nex.begin(); nex.erase(nex.begin());
for (int x: radj[a.s]) {
if (p[x].top()+a.f < cur[x]) {
nex.erase({cur[x],x});
cur[x] = p[x].top()+a.f;
nex.insert({cur[x],x});
}
p[x].pop();
}
}
cout << cur[1];
}
/* Look for:
* the exact constraints (multiple sets are too slow for n=10^6 :( )
* special cases (n=1?)
* overflow (ll vs int?)
* array bounds
*/
