E.cpp

// #pragma GCC optimize("Ofast,unroll-loops")
// #pragma GCC target("avx,avx2,fma")

#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define ull unsigned long long
#define dd double
#define ld long double
#define sl(n) scanf("%lld", &n)
#define si(n) scanf("%d", &n)
#define sd(n) scanf("%lf", &n)
#define pll pair <ll, ll>
#define pii pair <int, int>
#define mp make_pair
#define pb push_back
#define all(v) v.begin(), v.end()
#define inf (1LL << 61)
#define loop(i, start, stop, inc) for(ll i = start; i <= stop; i += inc)
#define for1(i, stop) for(ll i = 1; i <= stop; ++i)
#define for0(i, stop) for(ll i = 0; i < stop; ++i)
#define rep1(i, start) for(ll i = start; i >= 1; --i)
#define rep0(i, start) for(ll i = (start-1); i >= 0; --i)
#define ms(n, i) memset(n, i, sizeof(n))
#define casep(n) printf("Case %lld:", ++n)
#define pn printf("\n")
#define pf printf
#define EL '\n'
#define fastio std::ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);

const ll sz = 2e5 + 10;
map <int, char> w[sz];

int main()
{
    set <pii> both, bothSame;

    ll n, m;
    cin >> n >> m;

    for1(i, m) {
        char op;
        scanf(" %c", &op);

        if(op == '?') {
            ll k; sl(k);

            if(k & 1)
                pf("%s\n", both.empty()? "NO" : "YES");
            else
                pf("%s\n", bothSame.empty()? "NO" : "YES");
        }
        else {
            char ch;
            ll u, v;
            scanf("%lld %lld", &u, &v);

            ll tu = u, tv = v;
            if(tu > tv) swap(tu, tv);

            if(op == '-') {
                both.erase(mp(tu, tv));
                bothSame.erase(mp(tu, tv));

                w[u].erase(v);
            }
            else {
                scanf(" %c", &ch);

                if(w[v].find(u) != w[v].end()) {
                    both.insert(mp(tu, tv));

                    if(w[v][u] == ch)
                        bothSame.insert(mp(tu, tv));
                }
                w[u][v] = ch;
            }
        }
    }

    return 0;
}