#include <cstdio>

#include <iostream>

#include <algorithm>

#define N 500001

int n, m, q, cnt, tot, size;

int sum[N * 10], ls[N * 10], rs[N * 10], a[N], b[N], f[N], root[N], ans[N], c[N << 1];

struct node

{

	int x, y, z, id;

	node(int x = 0, int y = 0, int z = 0, int id = 0) : x(x), y(y), z(z), id(id) {}

}p[N], ask[N];

inline int read()

{

	int x = 0, f = 1;

	char ch = getchar();

	for(; !isdigit(ch); ch = getchar()) if(ch == '-') f = -1;

	for(; isdigit(ch); ch = getchar()) x = (x << 1) + (x << 3) + ch - '0';

	return x * f;

}

inline bool cmp1(node x, node y)

{

	return x.z < y.z;

}

inline bool cmp2(node x, node y)

{

	return x.y < y.y;

}

inline void merge(int &x, int y)

{

	if(!x || !y)

	{

		x += y;

		return;

	}

	sum[x] += sum[y];

	merge(ls[x], ls[y]);

	merge(rs[x], rs[y]);

}

inline void insert(int &now, int l, int r, int x)

{

	now = ++size;

	if(l == r)

	{

		sum[now] = 1;

		return;

	}

	int mid = (l + r) >> 1;

	if(x <= mid) insert(ls[now], l, mid, x);

	else insert(rs[now], mid + 1, r, x);

	sum[now] = sum[ls[now]] + sum[rs[now]];

}

inline int query(int now, int l, int r, int x)

{

	if(l == r) return l;

	int mid = (l + r) >> 1;

	if(x <= sum[ls[now]])

		return query(ls[now], l, mid, x);

	else

		return query(rs[now], mid + 1, r, x - sum[ls[now]]);

}

inline int find(int x)

{

	return x == f[x] ? x : f[x] = find(f[x]);

}

int main()

{

	int i, j, x, y, z;

	n = read();

	m = read();

	q = read();

	for(i = 1; i <= n; i++) a[i] = b[i] = read();

	std::sort(b + 1, b + n + 1);

	cnt = std::unique(b + 1, b + n + 1) - b - 1;

	for(i = 1; i <= n; i++)

	{

		a[i] = std::lower_bound(b + 1, b + cnt + 1, a[i]) - b;

		f[i] = i;

		insert(root[i], 1, cnt, a[i]);

	}

	for(i = 1; i <= m; i++)

	{

		x = read();

		y = read();

		c[i] = z = read();

		p[i] = node(x, y, z, 0);

	}

	for(i = 1; i <= q; i++)

	{

		x = read();

		c[i + m] = y = read();

		z = read();

		ask[i] = node(x, y, z, i);

	}

	std::sort(c + 1, c + m + q + 1);

	tot = std::unique(c + 1, c + m + q + 1) - c - 1;

	for(i = 1; i <= m; i++)

		p[i].z = std::lower_bound(c + 1, c + tot + 1, p[i].z) - c;

	for(i = 1; i <= q; i++)

		ask[i].y = std::lower_bound(c + 1, c + tot + 1, ask[i].y) - c;

	std::sort(p + 1, p + m + 1, cmp1);

	std::sort(ask + 1, ask + q + 1, cmp2);

	j = 1;

	for(i = 1; i <= q; i++)

	{

		while(j <= m && p[j].z <= ask[i].y)

		{

			x = find(p[j].x);

			y = find(p[j].y);

			if(x ^ y)

			{

				f[y] = x;

				merge(root[x], root[y]);

			}

			j++;

		}

		x = find(ask[i].x);

		if(ask[i].z > sum[root[x]]) ans[ask[i].id] = -1;

		else ans[ask[i].id] = b[query(root[x], 1, cnt, sum[root[x]] - ask[i].z + 1)];

	}

	for(i = 1; i <= q; i++) printf("%d\n", ans[i]);

	return 0;

}