#include<bits/stdc++.h>
using namespace std;
const int N = 110;
struct edge{int x,y,w;};
vector<edge>E;
int n,m,rt,in[N],pre[N],scc[N],vis[N];
int solve()
{
	int ans=0;
	while(True)
	{
		memset(in, 0x3f, sizeof(in));
		memset(pre, 0, sizeof(pre));
		memset(scc, 0, sizeof(scc));
		memset(vis, 0, sizeof(vis));
		
		for(auto e:E)if(e.x!=e.y && e.w<in[e.y])in[e.y]=e.w,pre[e.y]=e.x;
		for(int i=1;i<=n;++i)if(i!=rt&&pre[i]==0) return -1;
		for(int i=1;i<=n;++i)if(i!=rt)ans+=in[i];
		
		int cnt = 0;
		for(int i=1,x;i<=n;++i)if(!scc[i])
		{
			for(x=i; x!=rt && !scc[x] && vis[x]!=i; x=pre[x]) vis[x]=i;
			if(x!=rt && !scc[x])
			{
				for(++cnt;!scc[x];x=pre[x]) scc[x]=cnt;
			}
		}
		if(cnt==0) return ans;
		for(int i=1;i<=n;++i)if(!scc[i]) scc[i]=++cnt;
		
		for(int i=0;i<E.size();i++)
		{
			E[i].w=E[i].w-in[E[i].y];
			E[i].x=scc[E[i].x];E[i].y=scc[E[i].y];
		}
		n=cnt;
		rt=scc[rt];
	}
}
int main()
{
	scanf("%d%d%d",&n,&m,&rt);
	for(int i=1,x,y,w;i<=m;++i)
	{
		scanf("%d%d%d",&x,&y,&w);if(x==y||y==rt) continue;
		E.push_back(edge{x,y,w});
	}
	printf("%d",solve());
	return 0;
}