MS-DOS

#include <algorithm>
#include <iostream>
#include <string>
#include <cstring>

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef unsigned int uint;

using namespace std;

string s[20000], ans;
int n, u = 0, o;

void check(int r, int t)
{
    string st, s1;
    int y = 0;
    for (int i = 0; i < r; i++)
        st += s[i] + (char)92;
    st += "...";
    st += (char)92;
    for(int i = t; i < n; i++)
        s1 += s[i] + (char)92;
    s1.resize(s1.size() - 1);
    st += s1;
    if (st.size() > o) return;
    if (st.size() > ans.size() || (st.size() == ans.size() && s1.size() > u))
        ans = st, u = s1.size();
}

int main()
{
    char c;
    cin >> o;
    while (cin >> c)
    {
        if (c == 92) n++;
        else s[n] += c;
    }
    n++;
    for (int i = 0; i < n; i++) ans += s[i] + (char)92;
    ans.resize(ans.size() - 1);
    if (o >= ans.size()) return cout << ans, 0;
    ans = "";
    for (int i = 2; i < n - 1; i++)
        for (int j = i + 1; j < n; j++)
            check(i, j);
    cout << ans;
    return 0;
}