всош до первого бел или черн с конца и нач

#include <iostream>
#include <cmath>
#include <vector>
#include <queue>
#include <algorithm>
#include <string>
#include <stack>
#include <set>
#include <map>
#define pii pair <int, int>
#define pb(x) push_back(x)
using namespace std;
using ll = long long;
using ld = long double;
using db = double;
void cv(vector <int> &v) {
    for (auto x : v) cout << x << ' ';
    cout << "\n";
}

void cvl(vector <ll> &v) {
    for (auto x : v) cout << x << ' ';
    cout << "\n";
}


void cvv(vector <vector <int> > &v) {
    for (auto x : v) cv(x);
    cout << "\n";
}

void cvb(vector <bool> v) {
    for (bool x : v) cout << x << ' ';
    cout << "\n";
}

void cvs(vector <string>  v) {
    for (auto a : v) {
        cout << a << "\n";
    }
}

void cvp(vector <pii> a) {
    for (auto p : a) {
        cout << p.first << ' ' << p.second << "\n";
    }
    cout << "\n";
}



int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int n;
    cin >> n;
    vector <int> a(n); for (int &i: a) cin >> i;
    int b1 = -1, blt = -1, w1 = -1, wlt = -1;
    for (int i = 0; i < n && (b1 == -1 || w1 == -1); ++i) {
        if (a[i] == 1 && w1 == -1) {
            w1 = i;
        }
        if (a[i] == 2 && b1 == -1) {
            b1 = i;
        }
    }
    for (int i = n - 1; i >= 0 && (blt == -1 || wlt == -1); --i) {
        if (a[i] == 1 && wlt == -1) {
            wlt = i;
        }
        if (a[i] == 2 && blt == -1) {
            blt = i;
        }
    }
    int bup = 0, wup = 0, bdn = 0, wdn = 0;
    for (int i = 0 ; i < wlt; ++i) {
        if (a[i] == 2) {
            wup++;
        }
    }
    for (int i = 0; i < blt; ++i) {
        if (a[i] == 1) {
            bup++;
        }
    }
    for (int i = n - 1; i > w1; --i) {
        if (a[i] == 2) {
            wdn++;
        }
    }
    for (int i = n - 1; i > b1; --i) {
        if (a[i] == 1) {
            bdn++;
        }
    }
    int up = min(wup, bup), dn = min(bdn, wdn), ans = min(up, dn);
    cout << ans;
}