#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
#define int long long
using namespace std;
const int maxn = 200001, inf = 0x3f3f3f3f;
priority_queue<pair<int, int >, vector<pair <int, int> >, greater< pair<int, int > > > q ;
int n, m, s, ans;
int head[maxn], head1[maxn], dis[maxn];
bool vis[maxn];
struct node
{
	int next, to, w;
} e[maxn], e1[maxn];
void add1(int u, int v, int w, int step)
{
	e[step].to = v;
	e[step].w = w;
	e[step].next = head[u];
	head[u] = step;
}
void add2(int u, int v, int w, int step)
{
	e1[step].to = v;
	e1[step].w = w;
	e1[step].next = head1[u];
	head1[u] = step;
}
void Dijstra1(int s)
{
	memset(vis, false, sizeof(vis));
	memset(dis, inf, sizeof(dis));
	dis[s] = 0;
	q.push({0, s});
	while (!q.empty())
	{
		int x = q.top().second;
		q.pop();
		if (vis[x]) continue;
		vis[x] = true;
		for (int i = head1[x]; i; i = e[i].next)
		{
			int v = e[i].to;
			if (dis[v] > dis[x] + e[i].w)
			{
				dis[v] = dis[x] + e[i].w;
				q.push({dis[v], v});
			}
		}
	}
}
void Dijstra2(int s)
{
	memset(vis, false, sizeof(vis));
	memset(dis, inf, sizeof(dis));
	dis[s] = 0;
	q.push({0, s});
	while (!q.empty())
	{
		int x = q.top().second;
		q.pop();
		if (vis[x]) continue;
		vis[x] = true;
		for (int i = head1[x]; i; i = e1[i].next)
		{
			int v = e1[i].to;
			if (dis[v] > dis[x] + e1[i].w)
			{
				dis[v] = dis[x] + e1[i].w;
				q.push({dis[v], v});
			}
		}
	}
}
signed main()
{
	//freopen("in.txt", "r", stdin);

	scanf("%lld %lld %lld", &n, &m, &s);
	for (int i = 1; i <= m; i++)
	{
		int u, v, w;
		scanf("%lld %lld %lld", &u, &v, &w);
		add1(u, v, w, i);
		add2(v, u, w, i);
	}
	Dijstra1(s);
	for (int i = 1; i <= n; i++)
	{
		ans += dis[i];
	}
	Dijstra2(s);
	for (int i = 1; i <= n; i++)
	{
		ans += dis[i];
	}
	printf("%lld\n", ans);
	return 0;
}