#include <bits/stdc++.h>
using namespace std;
const int maxn = 50000;
const int maxo = 10000;
const int maxk = 5;
const int logn = 19;
const int INF = 1e9;
int k, n, m, o;
pair<int,int> orders[maxo];
int dp[maxn][logn][maxk][maxk]; // from k*maxn+maxk1 --> k*(maxn+2^logn) + maxk2
inline void comb(int a2[maxk][maxk], int a[maxk][maxk], int m[maxk][maxk]) {
for (int i = 0; i < k; i++)
for (int j = 0; j < k; j++)
for (int l = 0; l < k; l++)
a2[i][l] = min(a2[i][l], a[i][j] + m[j][l]);
}
int main() {
// freopen("main.in", "r", stdin);
fill(dp[0][0][0], dp[0][0][0] + maxn*logn*maxk*maxk, INF);
cin >> k >> n >> m >> o;
for (int i = 0; i < m; i++) {
int a, b, t; cin >> a >> b >> t;
dp[a / k][0][a%k][b%k] = t;
}
// for (int i = 0; i <= 1; i++) {
// for (int a = 0; a < 5; a++) {
// for (int b = 0; b < 5; b++) {
// cout << dp[i][0][a][b] << ' ';
// }
// cout << endl;
// }
// }
// set up binary lifting
for (int i = 1; i < logn; i++) { // for each power of 2 jump
for (int j = 0; j + (1 << i) <= (n-k+1)/k; j++) { // do all j where j+(power of 2) is still an actual section
comb(dp[j][i], dp[j][i-1], dp[j+(1<<(i-1))][i-1]);
}
}
int ans[maxk][maxk], ans2[maxk][maxk];
for (int i = 0; i < o; i++) {
int a, b; cin >> a >> b;
int A = a/k, B = b/k;
fill(ans[0], ans[0] + maxk*maxk, INF);
for (int j = 0; j < k; j++) ans[j][j] = 0;
// ans[a%k][a%k] = 0; // because we are starting at a%k, and only care about paths from it
// a->b where a =/= b doesn't make sense since we haven't made jumps, and rest we aren't starting at it
for (int j = logn-1; j >= 0; j--)
if (((B-A)>>j) & 1) {
// make jump of size j
fill(ans2[0], ans2[0] + maxk*maxk, INF);
comb(ans2, ans, dp[A][j]);
A += (1<<j);
for (int c = 0; c < k; c++)
for (int d = 0; d < k; d++)
ans[c][d] = ans2[c][d];
}
cout << (ans[a%k][b%k] == INF ? -1 : ans[a%k][b%k]) << endl;
}
return 0;
}
