#include <bits/stdc++.h>
using namespace std;
//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pi;
#define pb push_back
#define mp make_pair
#define f first
#define s second
int k, n, m, o;
int ans[5][5], temp[5][5], dp[50000][17][5][5];
void combine(int t[5][5], int a[5][5], int b[5][5]){
for(int i = 0; i < k; i++){
for(int j = 0; j < k; j++){
for(int l = 0; l < k; l++){
t[i][j] = min(t[i][j], a[i][l] + b[l][j]);
}
}
}
}
void solve(){
cin >> k >> n >> m >> o;
int INF = 1e9+7;
memset(dp, 0x3f, sizeof dp);
for(int i = 0; i < m; i++){
int a, b, w;
cin >> a >> b >> w;
dp[a/k][0][a % k][b % k] = w;
}
//dp[i][y][j][l] cel mai scurt drum de la k*i + j de la k*(i + 2^y - 1) + l;
//dp[i][y][j][l] = dp[i][y-1][j][temp] + dp[i + 2^(y-1)[y-1][temp][l];
for(int y = 1; y < 17; y++){
for(int i = 0; i + (1 << y) < (n + k - 1) / k; i++){
combine(dp[i][y], dp[i][y-1], dp[i + (1 << (y-1))][y-1]);
}
}
for(int u = 0; u < o; u++){
int a, b;
cin >> a >> b;
memset(ans, 0x3f, sizeof ans);
for (int i = 0; i < 5; i++)
ans[i][i] = 0;
ll ord1 = a/k, ord2 = b/k, mod1 = a % k, mod2 = b % k;
for (int i = 16; i >= 0; i--) {
if (ord1 + (1 << i) <= ord2) {
memset(temp, 0x3f, sizeof temp);
combine(temp, ans, dp[ord1][i]);
memcpy(ans, temp, sizeof ans);
ord1 += (1 << i);
}
}
if(ans[mod1][mod2] == 0x3f3f3f3f)
cout << -1 << '\n';
else
cout << ans[mod1][mod2] << '\n';
}
}
int main(){
//freopen("infasuratoare.in", "r", stdin);
//freopen("infasuratoare.out", "w", stdout);
ios::sync_with_stdio(0); cin.tie(0);
int t = 1;
//cin >> t;
while(t--){
solve();
}
}
