#include<iostream>
#include<cstring>
#include<cmath>
#include<vector>
#include<queue>
#include<deque>
#include<cstdio>
#include<algorithm>
#include<string>
#include<list>
#define int long long
#define itn int
#pragma GCC optimize(3)
#pragma GCC optimize(2)
#pragma GCC target("avx")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("inline")
#pragma GCC optimize("-fgcse")
#pragma GCC optimize("-fgcse-lm")
#pragma GCC optimize("-fipa-sra")
#pragma GCC optimize("-ftree-pre")
#pragma GCC optimize("-ftree-vrp")
#pragma GCC optimize("-fpeephole2")
#pragma GCC optimize("-ffast-math")
#pragma GCC optimize("-fsched-spec")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("-falign-jumps")
#pragma GCC optimize("-falign-loops")
#pragma GCC optimize("-falign-labels")
#pragma GCC optimize("-fdevirtualize")
#pragma GCC optimize("-fcaller-saves")
#pragma GCC optimize("-fcrossjumping")
#pragma GCC optimize("-fthread-jumps")
#pragma GCC optimize("-funroll-loops")
#pragma GCC optimize("-fwhole-program")
#pragma GCC optimize("-freorder-blocks")
#pragma GCC optimize("-fschedule-insns")
#pragma GCC optimize("inline-functions")
#pragma GCC optimize("-ftree-tail-merge")
#pragma GCC optimize("-fschedule-insns2")
#pragma GCC optimize("-fstrict-aliasing")
#pragma GCC optimize("-fstrict-overflow")
#pragma GCC optimize("-falign-functions")
#pragma GCC optimize("-fcse-skip-blocks")
#pragma GCC optimize("-fcse-follow-jumps")
#pragma GCC optimize("-fsched-interblock")
#pragma GCC optimize("-fpartial-inlining")
#pragma GCC optimize("no-stack-protector")
#pragma GCC optimize("-freorder-functions")
#pragma GCC optimize("-findirect-inlining")
#pragma GCC optimize("-fhoist-adjacent-loads")
#pragma GCC optimize("-frerun-cse-after-loop")
#pragma GCC optimize("inline-small-functions")
#pragma GCC optimize("-finline-small-functions")
#pragma GCC optimize("-ftree-switch-conversion")
#pragma GCC optimize("-foptimize-sibling-calls")
#pragma GCC optimize("-fexpensive-optimizations")
#pragma GCC optimize("-funsafe-loop-optimizations")
#pragma GCC optimize("inline-functions-called-once")
#pragma GCC optimize("-fdelete-null-pointer-checks")
#pragma GCC optimize("Ofast", "inline", "-ffast-math")
#pragma GCC target("avx,sse2,sse3,sse4,mmx")
#pragma GCC optimize("-fgcse")
#define DEBUG printf("Baylor AK IOI\n");
#pragma GCC optimize("Ofast,unroll-loops,fast-math")
#pragma GCC target("ssse3","sse3","sse2","sse","avx2","avx")
#pragma GCC optimize("Ofast","-funroll-loops","-fdelete-null-pointer-checks")
using namespace std;
int top,id,minn,sum,head[100005],to[100005],ne[100005],dis[100005],vis[100005],w[1000005],n;
void init(int x,int y,int z){
	to[++top]=y;
	w[top]=z;
	ne[top]=head[x],head[x]=top;
	return;
} 
inline int prim(){
	memset(dis,0x3f,sizeof(dis));
	dis[1]=0;
	sum=0;
	for(int i=1;i<=n;i++){
		id=-1,minn=100000;
		for(int j=1;j<=n;j++){
			if(!vis[j]&&dis[j]<minn){
				minn=dis[j];
				id=j;
			}
		}
		vis[id]=1;
		sum+=minn;
		for(int j=head[id];j;j=ne[j]){
			if(!vis[to[j]]&&w[j]<dis[to[j]]){
				dis[to[j]]=w[j];
			}
		}
	}
	return sum;
}
signed main(){
	scanf("%lld",&n);
	for(int k=1;k<=n;k++){
		for(int i=1;i<=n;i++){
			int x;
			cin>>x;
			if(x==0)continue;
			else{
				init(k,i,x);
				init(i,k,x);			
			}
		}
	}
	int s=prim();
	cout<<s;
	return 0;
}
//register
//unsigned
//system("pause");
//system("cls");
//system("color OA");   0b  fc 75