#include<iostream>
#include<algorithm>
using namespace std;
typedef long long LL;
const int N = 10010, M = 87000;
const LL INF = 1e18;
int n,m,e;
struct Range{
int l,r,w;
}range[N];
struct Node{
int l,r;
LL v;
}tr[M*4];
bool cmp(Range A,Range B){
return A.r<B.r;}
void pushup(int u)
{
tr[u].v=min(tr[u<<1].v,tr[u<<1|1].v);
}
void build(int u,int l,int r)
{
tr[u]={
l,r,INF};
if(l==r) return;
else
{
int mid=l+r>>1;
build(u<<1,l,mid);build(u<<1|1,mid+1,r);
}
}
void update(int u,int k,LL v)
{
if(tr[u].l==tr[u].r)
{
tr[u].v=min(tr[u].v,v);
return ;
}
else
{
int mid=tr[u].l+tr[u].r>>1;
if(k<=mid) update(u<<1,k,v);
else update(u<<1|1,k,v);
pushup(u);
}
}
LL query(int u,int l,int r)
{
if(tr[u].l>=l&&tr[u].r<=r) return tr[u].v;
else
{
int mid=tr[u].l+tr[u].r>>1;
LL res=INF;
if(l<=mid) res=query(u<<1,l,r);
if(r>mid) res=min(res,query(u<<1|1,l,r));
return res;
}
}
int main()
{
cin>>n>>m>>e;
build(1,m-1,e);
update(1,m-1,0);
for(int i=0;i<n;i++) cin>>range[i].l>>range[i].r>>range[i].w;
sort(range,range+n,cmp);
for(int i=0;i<n;i++)
{
int l=range[i].l,r=range[i].r,w=range[i].w;
LL v=query(1,l-1,r-1)+w;
update(1,r,v);
}
LL res=query(1,e,e);
if(res==INF) res=-1;
cout<<res<<endl;
return 0;
}