Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func getScanner(fp *os.File) *bufio.Scanner {
	scanner := bufio.NewScanner(fp)
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 500001), 500000)
	return scanner
}

func getNextString(scanner *bufio.Scanner) string {
	scanner.Scan()
	return scanner.Text()
}

func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}

func main() {
	fp := os.Stdin
	if len(os.Args) > 1 {
		fp, _ = os.Open(os.Args[1])
	}

	scanner := getScanner(fp)
	writer := bufio.NewWriter(os.Stdout)

	n := getNextInt(scanner)

	g := make([][]int, n)
	ans := make([][]int, n)

	inf := 1 << 30
	for i := 0; i < n; i++ {
		g[i] = make([]int, n)
		ans[i] = make([]int, n)
		for ii := 0; ii < n; ii++ {
			g[i][ii] = getNextInt(scanner)
			if g[i][ii] == -1 {
				g[i][ii] = inf
			}
			ans[i][ii] = -1
		}
	}

	im := make(IntMap, 1)

	im.increment(1)

	for len(im) < n {
		min := inf
		u := -1
		v := -1
		for i := range im {
			for ii := 0; ii < n; ii++ {
				if im.get(ii) != 0 {
					continue
				}
				if min > g[i][ii] {
					min = g[i][ii]
					u = i
					v = ii
				}
			}
		}
		im.increment(v)
		ans[u][v] = min
		ans[v][u] = min
	}

	sum := 0
	for i := 0; i < n-1; i++ {
		for ii := i + 1; ii < n; ii++ {
			if ans[i][ii] != -1 {
				sum += ans[i][ii]
			}
		}
	}

	fmt.Fprintln(writer, sum)
	writer.Flush()
}

// IntMap ...
type IntMap map[int]int

func (m IntMap) get(key int) int {
	if _, ok := m[key]; ok {
		return m[key]
	}
	return 0
}
func (m IntMap) increment(key int) {
	if _, ok := m[key]; ok == false {
		m[key] = 0
	}
	m[key]++
}

C++: #include <iostream>
using namespace std;
#define MAX 100
#define INFINITY (1<<30)
enum{
	white=0,
	gray=1,
	black=2,
};

int n,m[MAX][MAX];

int prim(){
	int u,minv;
	int d[MAX],p[MAX],color[MAX];
	for(int i=0;i<n;i++){
		d[i]=INFINITY;
		p[i]=-1;
		color[i]=white;
	}
	d[0]=0;
	while(1){
		minv=INFINITY;
		u=-1;
		for(int i=0;i<n;i++){
			if(minv>d[i]&&color[i]!=black){
				u=i;
				minv=d[i];
			}
		}
		if(u==-1)	break;
		color[u]=black;
		for(int v=0;v<n;v++){
			if(color[v]!=black&&m[u][v]!=INFINITY){
				if(d[v]>m[u][v]){
					d[v]=m[u][v];
					p[v]=u;
					color[v]=gray;
				}
			}
		}
	}
	int sum=0;
	for(int i=0;i<n;i++){
		if(p[i]!=-1)	sum+=m[i][p[i]];
	}
	return sum;
}

int main(){
	cin>>n;
	int e;
	for(int i=0;i<n;i++){
		for(int j=0;j<n;j++){
			cin>>e;
			if(e==-1)	m[i][j]=INFINITY;
			else	m[i][j]=e;
		}
	}
	cout<<prim()<<endl;
	return 0;
}