Ответ:

#include <iostream>

#include <map>

#include <vector>

#include <set>

#include <stack>

#include <bitset>

#include <queue>

#include <algorithm>

#include <iomanip>

#include <unordered_map>

#include <unordered_set>

#include <cmath>

#include <cassert>

#include <random>

#pragma GCC target("avx,avx2,sse3,ssse3,sse4.1,sse4.2,tune=native")

#pragma GCC optimize(3)

#pragma GCC optimize("O3")

#pragma GCC optimize("inline")

#pragma GCC optimize("-fgcse")

#pragma GCC optimize("-fgcse-lm")

#pragma GCC optimize("-fipa-sra")

#pragma GCC optimize("-ftree-pre")

#pragma GCC optimize("-ftree-vrp")

#pragma GCC optimize("-fpeephole2")

#pragma GCC optimize("-fsched-spec")

#pragma GCC optimize("-falign-jumps")

#pragma GCC optimize("-falign-loops")

#pragma GCC optimize("-falign-labels")

#pragma GCC optimize("-fdevirtualize")

#pragma GCC optimize("-fcaller-saves")

#pragma GCC optimize("-fcrossjumping")

#pragma GCC optimize("-fthread-jumps")

#pragma GCC optimize("-freorder-blocks")

#pragma GCC optimize("-fschedule-insns")

#pragma GCC optimize("inline-functions")

#pragma GCC optimize("-ftree-tail-merge")

#pragma GCC optimize("-fschedule-insns2")

#pragma GCC optimize("-fstrict-aliasing")

#pragma GCC optimize("-falign-functions")

#pragma GCC optimize("-fcse-follow-jumps")

#pragma GCC optimize("-fsched-interblock")

#pragma GCC optimize("-fpartial-inlining")

#pragma GCC optimize("no-stack-protector")

#pragma GCC optimize("-freorder-functions")

#pragma GCC optimize("-findirect-inlining")

#pragma GCC optimize("-fhoist-adjacent-loads")

#pragma GCC optimize("-frerun-cse-after-loop")

#pragma GCC optimize("inline-small-functions")

#pragma GCC optimize("-finline-small-functions")

#pragma GCC optimize("-ftree-switch-conversion")

#pragma GCC optimize("-foptimize-sibling-calls")

#pragma GCC optimize("-fexpensive-optimizations")

#pragma GCC optimize("inline-functions-called-once")

#pragma GCC optimize("-fdelete-null-pointer-checks")

using namespace std;

void solve();

int main() {

   ios::sync_with_stdio(0);

   cin.tie(0);

#ifdef DEBUG

   freopen("input.txt", "r", stdin);

#endif

   solve();

}

const int N = 3e5 + 100, A = 2e5 + 100, MOD = 1e9 + 7, INF = 1e18;

int n;

string s;

void solve() {

   cin >> n >> s;

   for (int i = 1; i < n; i++) {

       s[i] = '0';

   }

   cout << s;

}

Объяснение: