ural 1080. Map Coloring

#include <stdio.h>
#include <stdlib.h>
#include <iostream>
using namespace std;
const int MAX = 110;
int n;
bool map[MAX][MAX];
int c[MAX];
bool used[MAX];
bool flag;
void DFS(int x)
{
	used[x] = 1;
	for(int i=1; i<=n; i++)
	{
		if( x == i ) continue;
		if( map[x][i] && c[i] && c[i] + c[x] != 0 )
		{
			flag = true;
			return;
		}
		if( map[x][i] && !c[i] && !used[i] )
		{
			if( c[x] == 1 )
				c[i] = -1;
			else
				c[i] = 1;
			DFS(i);
			if( flag )
				return ;
		}
	}
}
int main()
{
	int t;
	memset(c,0,sizeof(c));
	memset(map,false,sizeof(map));
	scanf("%d",&n);
	for(int i=1; i<=n; i++)
		while( scanf("%d",&t) && t )
			map[i][t] = map[t][i] = 1;
			
	flag = 0;
	for(int i=1; i<=n && !flag; i++)
	{
		if( !used[i] ) 
			c[i] = 1;
		DFS(i);
	}
	if( flag )
		printf("-1/n");
	else
	{
		for(int i=1; i<=n; i++)
			if( c[i] == 1 )
				printf("0");
			else
				printf("1");
		printf("/n");
	}
	return 0;
}