#include<bits/stdc++.h>
using namespace std;
const int N=20005,M=50005;

int n,m,q;
int fa[N];

struct E{int u,v,w,id;}e[M],tmp[M];

int find(int x){return fa[x]==x?x:fa[x]=find(fa[x]);}

long long kruskal(){
	for(int i=1;i<=m;i++)tmp[i]=e[i];
	sort(tmp+1,tmp+m+1,[](E&a,E&b){return a.w<b.w;});
	for(int i=1;i<=n;i++)fa[i]=i;
	long long ans=0;int cnt=0;
	for(int i=1;i<=m;i++){
		int u=find(tmp[i].u),v=find(tmp[i].v);
		if(u!=v){fa[u]=v;ans+=tmp[i].w;if(++cnt==n-1)break;}
	}
	return ans;
}

int main()
{
	freopen("hnoi2010_city.in","r",stdin);
	freopen("hnoi2010_city.out","w",stdout);
	scanf("%d%d%d",&n,&m,&q);
	for(int i=1;i<=m;i++){scanf("%d%d%d",&e[i].u,&e[i].v,&e[i].w);e[i].id=i;}
	while(q--)
	{
		int k,d;scanf("%d%d",&k,&d);
		for(int i=1;i<=m;i++)if(e[i].id==k){e[i].w=d;break;}
		printf("%lld\n",kruskal());
	}
	return 0;
}