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codevs1003

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#include<iostream>
#include<cstdio>
using namespace std;
int dis[],map[][],n,num,cost,fa[],point[];
bool vis[];
void Prim(int s,int t){
    for(int i=;i<=n;i++)dis[i]=0x7f;
    dis[s]=;int pre=;
    for(int i=;i<=n;i++){
        int Min=0x7f,k=;
        for(int j=;j<=n;j++){
            if((dis[j]<Min)&&(vis[j]==))
            Min=dis[j],k=j,point[num]=k;
        }
        if(Min==0x7f)break;
        cost+=Min;
        vis[k]=;
        for(int j=;j<=n;j++){
            if((map[k][j]<dis[j])&&(vis[j]==))dis[j]=map[k][j],fa[j]=k;
        }
        if(Min!=)num++;
        pre=k;
    }
}
int main(){
    scanf("%d",&n);
    for(int i=;i<=n;i++)
        for(int j=;j<=n;j++)
            cin>>map[i][j];
    Prim(,n);
    cout<<num<<endl;
    for(int i=;i<num;i++)
    if(fa[point[i]]<point[i])cout<<fa[point[i]]<<' '<<point[i]<<endl;
    else cout<<point[i]<<' '<<fa[point[i]]<<endl;
    cout<<cost;
}