#include<bits/stdc++.h>
using namespace std;
int n,m,qq,fa[200005],p[200005],x[50005],y[50005],z[50005],ds[2000005],xx,yy;
long long as;
vector<pair<int,int> >v[200005];
priority_queue<pair<long long,int> >q;
inline int f(int x){
    if(fa[x]!=x) fa[x]=f(fa[x]);
    return fa[x];
}
int main(){
    freopen("hnoi2010_city.in","r",stdin);
    freopen("hnoi2010_city.out","w",stdout);
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
	cin>>n>>m>>qq;
    for(int i=1;i<=n;i++) fa[i]=i;
    for(int i=1;i<=m;i++) cin>>x[i]>>y[i]>>z[i];
    while(qq--){
        cin>>xx>>yy;
        z[xx]=yy,as=0;
        for(int i=1;i<=n;i++) v[i].clear(),ds[i]=1e9,p[i]=0;
        for(int i=1;i<=m;i++) v[x[i]].push_back({y[i],z[i]}),v[y[i]].push_back({x[i],z[i]});
        q.push({0,1});
        while(!q.empty()){
            int tp=q.top().second,pt=-q.top().first;
            q.pop();
            if(p[tp]) continue;
            p[tp]=1,as+=pt;
            for(int i=0;i<v[tp].size();i++){
                if(!p[v[tp][i].first]) q.push({-v[tp][i].second,v[tp][i].first});
            }
        }
        cout<<as<<"\n";
    }
	return 0;
}