Building Teams

input/code.cpp: In function 'int main()':
input/code.cpp:18:13: warning: unused variable 'shop' [-Wunused-variable]
   18 |         int shop;
      |             ^~~~
input/code.cpp:52:49: error: expected ';' before 'it_teams2'
   52 |         if(it_teams1 == team1.end()) printf("2") it_teams2++;
      |                                                 ^~~~~~~~~~
      |                                                 ;

#include <string>
#include <iostream>
#include <set>

using namespace std;

int main()
{
    int n_pups, n_friendships;
    cin >> n_pups >> n_friendships;
    set<int> team1;
    set<int> team2;
    int pup1, pup2;

    for(int i = 0; i < n_friendships; ++i)
    {
        cin >> pup1 >> pup2;
        int shop;
        if(team1.count(pup1))
        {
            if(!team1.count(pup2)) team1.insert(pup1), team2.insert(pup2);
            else {printf("IMPOSSIBLE\n"); break;}
        }
        else if(team2.count(pup1))
        {
            if(!team2.count(pup2)) team2.insert(pup1), team1.insert(pup2);
            else {printf("IMPOSSIBLE\n"); break;}
        }
        else if(team1.count(pup2))
        {
            if(!team1.count(pup1)) team1.insert(pup2), team2.insert(pup1);
            else {printf("IMPOSSIBLE\n"); break;}
        }
        else if(team2.count(pup2))
        {
            if(!team1.count(pup1)) team2.insert(pup2), team1.insert(pup1);
            else {printf("IMPOSSIBLE\n"); break;}
        }
        else
        {
            team1.insert(pup1);
            team2.insert(pup2);
        }
    }


    set<int>::iterator it_teams1 = team1.begin();
    set<int>::iterator it_teams2 = team2.begin();

    for(int i = 0; i < n_pups; ++i)
    {
        if(it_teams1 == team1.end()) printf("2") it_teams2++;
        else if(it_teams2 == team2.end()) printf("1"), it_teams1++;
        else if(*it_teams1 < *it_teams2) printf("1"), it_teams1++;
        else if(*it_teams1 > *it_teams2) printf("2"), it_teams2++;
    }
    return 0;
}