#include<bits/stdc++.h>
using namespace std;
using ll=long long;

int main(){
	ios::sync_with_stdio(false);
    cin.tie(nullptr);

    clock_t start=clock(),end=clock();
    ll N,M;
    cin>>N>>M;
    vector<vector<array<ll,2>>> G(N);
    for(int i=0;i<M;i++){
        ll u,v,w;
        cin>>u>>v>>w;
        u--;v--;
        G[u].push_back({v,w});
    }
    string S;
    cin>>S;
    ll an=1e18;
    while(double(end-start)/CLOCKS_PER_SEC<1.5){
        string T=S;
        for(int i=0;i<N;i++)if(T[i]=='C'){
            if(rand()%2==0)T[i]='U';
        }

        vector<vector<ll>> D(N,vector<ll>(4,1e18));
        D[0][0]=0;
        priority_queue<array<ll,3>,vector<array<ll,3>>,greater<array<ll,3>>> Q;
        Q.push({0,0,0});
        string TT="KUPC";
        vector<vector<bool>> seen(N,vector<bool>(4,0));
        while(!Q.empty()){
            auto [c,n,d]=Q.top();
            Q.pop();
            if(seen[n][d])continue;
            seen[n][d]=1;
            if(d==3&&T[n]=='C'){
                an=min(an,c);
                continue;
            }
            if(T[n]==TT[d])d++;
            for(auto [v,w]:G[n]){
                ll nc=w+c;
                if(D[v][d]<=nc)continue;
                D[v][d]=nc;
                Q.push({nc,v,d});
            }
        }


        end=clock();
    }
    if(an<1e17)cout<<an<<"\n";
    else cout<<-1<<"\n";
}