#include<cstdio>
#include<algorithm>
#include<iostream>
#include<cstring>
#define MAXN 101000
using namespace std;int ln[27][MAXN];
int rn[27][MAXN];
int top[27];
char s[MAXN];
int ans = 0;int main() {freopen("cross.in","r",stdin);freopen("cross.out","w",stdout);scanf("%s",s + 1);int len = strlen(s + 1);for(int i = 1; i <= len; i++) {s[i] = s[i] - 'a' + 1;if(ln[s[i]][top[s[i]]] == 0) {ln[s[i]][top[s[i]]] = i;} else if(rn[s[i]][top[s[i]]] == 0) {rn[s[i]][top[s[i]]] = i;for(int j = 1; j <= 26; j++) {if(j == s[i])continue;for(int k = top[j] - 1; k >= 0; k--) {if(ln[j][k] < ln[s[i]][top[s[i]]] && rn[j][k] > ln[s[i]][top[s[i]]]) {ans++;break;}if(rn[j][k] < ln[s[i]][top[s[i]]])break;}}top[s[i]]++;}}printf("%d",ans);return 0;
}

#include<queue>
#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cstring>
#define MAXN 5010
using namespace std;struct Edge {int vj;int wei;int nxt;
} edge1[MAXN * 4],edge2[MAXN * 4];
int now1,now2;
int head1[MAXN],head2[MAXN];struct Note {int now;int used;
} be;queue<Note>q;void push1(int vi,int vj,int wei) {now1++;edge1[now1].vj = vj;edge1[now1].wei = wei;edge1[now1].nxt = head1[vi];head1[vi] = now1;
}
void push2(int vi,int vj,int wei) {now2++;edge2[now2].vj = vj;edge2[now2].wei = wei;edge2[now2].nxt = head2[vi];head2[vi] = now2;
}
int read() {int nm = 0;char c = getchar();while(c < '0' || c > '9')c = getchar();while(c >= '0' && c <= '9') {nm *= 10;nm += c -'0';c = getchar();}return nm;
}int n,m,qq,k;int dis[MAXN][2050];
bool vis[MAXN][2050];int main() {freopen("move.in","r",stdin);freopen("move.out","w",stdout);n = read();m = read();qq = read();k = read();if(k > qq)k = qq;for(int i = 1; i <= m; i++) {int vi = read(),vj = read(),wei = read();push1(vi,vj,wei);}for(int i = 1; i <= qq; i++) {int vi = read(),vj = read(),wei = read();push2(vi,vj,wei);}memset(dis,0x3e,sizeof(dis));dis[1][0] = 0;be.now = 1;be.used = 0;q.push(be);while(!q.empty()) {Note op = q.front();q.pop();vis[op.now][op.used] = false;int now = op.now;int us = op.used;for(int i = head1[now]; i; i = edge1[i].nxt) {int vj = edge1[i].vj;if(dis[now][us] + edge1[i].wei < dis[vj][us]) {dis[vj][us] = dis[now][us] + edge1[i].wei;Note zz;zz.used = op.used;zz.now = vj;if(vis[zz.now][zz.used])continue;vis[zz.now][zz.used] = true;q.push(zz);}}if(op.used >= k)continue;for(int i = head2[now]; i; i = edge2[i].nxt) {int vj = edge2[i].vj;if(dis[now][us] + edge2[i].wei < dis[vj][us + 1]) {dis[vj][us + 1] = dis[now][us] + edge2[i].wei;Note zz;zz.used = op.used + 1;zz.now = vj;if(vis[zz.now][zz.used])continue;vis[zz.now][zz.used] = true;q.push(zz);}}}int ans = 0x3e3e3e3e;for(int i = 0; i <= min(k,qq); i++) {ans = min(ans,dis[n][i]);}printf("%d",ans == 0x3e3e3e3e ? -1:ans);return 0;
}