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1 #include<bits/stdc++.h>
2 #define ll long long
3 using namespace std;
4 const int P=1e6;
5 const int N=2e6+5;
6 const int M=2e6+5;
7 const int inf=0x3f3f3f3f;
8 struct edge
9 {
10 int f,t,next;
11 ll v;
12 }e[M];
13 int n,m,tot,all,s,cnt,head[N],dfn[N],low[N],st[N],id[N];
14 int dindex;
15 bool inst[N];
16 ll num[N],sum[100005],val[N];
17 void add(int f,int t,ll v)
18 {
19 e[tot].f=f; e[tot].t=t; e[tot].v=v;
20 e[tot].next=head[f]; head[f]=tot++;
21 }
22 void tarjan(int v)
23 {
24 dindex++;
25 dfn[v]=low[v]=dindex;
26 st[all++]=v; inst[v]=true;
27 for(int i=head[v];~i;i=e[i].next)
28 {
29 int nx=e[i].t;
30 if(!dfn[nx])
31 {
32 tarjan(nx);
33 low[v]=min(low[v],low[nx]);
34 }
35 else if(inst[nx]) low[v]=min(low[v],dfn[nx]);
36 }
37 if(dfn[v]==low[v])
38 {
39 cnt++;
40 while(1)
41 {
42 int cur=st[--all];
43 inst[cur]=false;
44 id[cur]=cnt;
45 if(cur==v) break;
46 }
47 }
48 }
49 ll work(ll x)
50 {
51 ll ans=0;
52 int item=lower_bound(num,num+15001,x)-num;
53 ans-=sum[item];
54 ans+=x*(item+1);
55 ans+=num[item]-x;
56 return ans;
57 }
58 ll dfs(int v)
59 {
60 ll res=0;
61 dfn[v]=1;
62 for(int i=head[v];~i;i=e[i].next)
63 {
64 int nx=e[i].t;
65 if(!dfn[nx]) res=max(res,e[i].v+dfs(nx));
66 else res=max(res,val[nx]+e[i].v);
67 }
68 val[v]+=res;
69 return val[v];
70 }
71 int main()
72 {
73 num[1]=1; cnt=0; all=0; tot=0; dindex=0;
74 for(int i=1;i<=15000;i++) num[i]=num[i-1]+i,sum[i]=sum[i-1]+num[i];
75 memset(head,-1,sizeof(head));
76 scanf("%d%d",&n,&m);
77 for(int i=1;i<=m;i++)
78 {
79 int f,t; ll v;
80 scanf("%d%d%lld",&f,&t,&v);
81 add(f,t,v);
82 }
83 scanf("%d",&s);
84 tarjan(s);
85 int up=tot;
86 for(int i=0;i<up;i++)
87 {
88 int a=e[i].f,b=e[i].t;
89 if(!id[a] || !id[b]) continue;
90 if(id[a]==id[b]) val[id[a]+P]+=work(e[i].v);
91 else if(id[a]<id[b]) add(id[b]+P,id[a]+P,e[i].v);
92 else add(id[a]+P,id[b]+P,e[i].v);
93 }
94 ll ans=dfs(id[s]+P);
95 printf("%lld
",ans);
96 return 0;
97 }
