# include <stdio.h>
# include <string.h>
# include <algorithm>
// # include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
const int M = 5e5 + 10;
const int mod = 1e9+7;

# define RG register
# define ST static

int n, K, m;

int x[M];
struct guard {
    int l, r;
    guard() {}
    guard(int l, int r) : l(l), r(r) {}
    friend bool operator < (guard a, guard b) {
        return a.l < b.l || (a.l == b.l && a.r > b.r);
    }
}a[M], o[M]; int on;

bool del[M];
int new_id[M], idx, old_id[M];
int pre[M], nxt[M];
int fp[M], fs[M];

namespace SMT {
    int w[M];
    # define ls (x<<1)
    # define rs (x<<1|1)
    inline void edt(int x, int l, int r, int L, int R) {
         if(w[x]) return;
        if(L <= l && r <= R) {
            w[x] = 1;
            return ;
        }
        int mid = l+r>>1;
        if(L <= mid) edt(ls, l, mid, L, R);
        if(R > mid) edt(rs, mid+1, r, L, R);
    }
    inline int query(int x, int l, int r, int pos) {
        if(w[x]) return 1;
        if(l == r) return 0;
        int mid = l+r>>1;
        if(pos <= mid) return query(ls, l, mid, pos);
        else return query(rs, mid+1, r, pos);
    }
    # undef ls
    # undef rs
}


int main() {
    scanf("%d%d%d", &n, &K, &m);
    for (int i=1; i<=m; ++i) scanf("%d%d%d", &a[i].l, &a[i].r, x+i);
    for (int i=1; i<=m; ++i) if(x[i] == 0) SMT::edt(1, 1, n, a[i].l, a[i].r);
    for (int i=1; i<=n; ++i) {
        if(SMT::query(1, 1, n, i) == 0) {
            new_id[i] = ++idx, old_id[idx] = i;
//            printf("i = %d, idx = %d\n", i, idx);
        }
        else del[i] = 1;
    }
    if(idx == K) {
        for (int i=1; i<=n; ++i) 
            if(!del[i]) printf("%d\n", i);
        return 0;
    }
    for (int i=1; i<=n; ++i) {
        if(!del[i]) pre[i] = i;
        else pre[i] = pre[i-1];
    }
    for (int i=n; i; --i) {
        if(!del[i]) nxt[i] = i;
        else nxt[i] = nxt[i+1];
    }
    for (int i=1; i<=m; ++i) {
        int nl = nxt[a[i].l], nr = pre[a[i].r];
        if(nl <= nr) o[++on] = guard(new_id[nl], new_id[nr]);
    }
    sort(o+1, o+on+1);
    m = 0;
    for (int i=1; i<=on; ++i) {
        while(m && o[i].l >= a[m].l && o[i].r <= a[m].r) --m;
        a[++m] = o[i];
    }
//    for (int i=1; i<=m; ++i) 
//        printf("%d %d\n", a[i].l, a[i].r);
    int cur = 0;
    for (int i=1; i<=m; ++i) 
        if(a[i].l > cur) fp[i] = fp[i-1] + 1, cur = a[i].r;
        else fp[i] = fp[i-1];
    cur = 1e9;
    for (int i=m; i; --i)
        if(a[i].r < cur) fs[i] = fs[i+1] + 1, cur = a[i].l;
        else fs[i] = fs[i+1];
    
    bool have_ans = 0; 
    
    for (int i=1, x, l, r, ans1, ans2; i<=m; ++i) {
        if(fp[i] != fp[i-1]+1) continue;
        if(a[i].l == a[i].r) {
            have_ans = 1;
//            printf("=%d\n", a[i].r);
            printf("%d\n", old_id[a[i].r]);
            continue;
        }
        // 考察每个区间的右端点是否可行
        x = a[i].r-1;
        l = 1, r = i-1, ans1 = 0;
        while(1) {
            if(r-l<=3) {
                for (int j=r; j>=l; --j) 
                    if(a[j].r < x) {
                        ans1 = j;
                        break;
                    }
                break;
            }
            int mid = l+r>>1;
            if(a[mid].r < x) l = mid;
            else r = mid;
        }
        l = i+1, r = m, ans2 = m+1;
        while(1) {
            if(r-l<=3) {
                for (int j=l; j<=r; ++j)
                    if(a[j].l > x) {
                        ans2 = j;
                        break;
                    }
                break;
            }
            int mid = l+r>>1;
            if(a[mid].l > x) r = mid;
            else l = mid;
        }
//        printf("%d %d\n", ans1, ans2);
        if(fp[ans1] + fs[ans2] + 1 > K) {
//            printf("=%d\n", a[i].r);
            printf("%d\n", old_id[a[i].r]);
            have_ans = 1;
        } 
    }
    
    if(!have_ans) puts("-1");

    return 0;
}