2840번: 행운의 바퀴 ↗

/*
[2840: 행운의 바퀴](https://www.acmicpc.net/problem/2840)

Tier: Silver 4 
Category: implementation, simulation
*/


#include <bits/stdc++.h>

using namespace std;

#define for1(s, e) for(int i = s; i < e; i++)
#define for1j(s, e) for(int j = s; j < e; j++)
#define forEach(k) for(auto i : k)
#define forEachj(k) for(auto j : k)
#define sz(vct) vct.size()
#define all(vct) vct.begin(), vct.end()
#define sortv(vct) sort(vct.begin(), vct.end())
#define uniq(vct) sort(all(vct));vct.erase(unique(all(vct)), vct.end())
#define fi first
#define se second
#define INF (1ll << 60ll)

typedef unsigned long long ull;
typedef long long ll;
typedef ll llint;
typedef unsigned int uint;
typedef unsigned long long int ull;
typedef ull ullint;

typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<double, double> pdd;
typedef pair<double, int> pdi;
typedef pair<string, string> pss;

typedef vector<int> iv1;
typedef vector<iv1> iv2;
typedef vector<ll> llv1;
typedef vector<llv1> llv2;

typedef vector<pii> piiv1;
typedef vector<piiv1> piiv2;
typedef vector<pll> pllv1;
typedef vector<pllv1> pllv2;
typedef vector<pdd> pddv1;
typedef vector<pddv1> pddv2;

const double EPS = 1e-8;
const double PI = acos(-1);

template<typename T>
T sq(T x) { return x * x; }

int sign(ll x) { return x < 0 ? -1 : x > 0 ? 1 : 0; }
int sign(int x) { return x < 0 ? -1 : x > 0 ? 1 : 0; }
int sign(double x) { return abs(x) < EPS ? 0 : x < 0 ? -1 : 1; }

ll n, k;
vector <char> ar;

void solve() {
  cin >> n >> k;

  ar.resize(n, '0');

  ll crt = 0;
  for1(0, k) {
    ll num;
    char a;

    cin >> num >> a;

    crt -= num;
    crt += n * 100000;
    crt %= n;

    if(ar[crt] == '0') ar[crt] = a;
    else if(ar[crt] != a) {
      cout << "!";
      return;
    }
  }

  for1(0, n) {
    for1j(i + 1, n) {
      if(ar[i] != '0' && ar[i] == ar[j]) {
        cout << "!";
        return;
      }
    }
  }

  for1(crt, n) {
    if(ar[i] == '0') cout << '?';
    else cout << ar[i];
  }

  for1(0, crt) {
    if(ar[i] == '0') cout << '?';
    else cout << ar[i];
  }
}

int main() {
  ios::sync_with_stdio(0);
  cin.tie(NULL);cout.tie(NULL);
  int tc = 1; // cin >> tc;
  while(tc--) solve();
  
}