abc216_b_same_name.cpp

// Same Name | https://atcoder.jp/contests/abc216/tasks/abc216_b
// Time: O(n L log n); extra space: O(n L).
#include <iostream>
#include <set>
#include <string>
#include <utility>

void solve() {
    int n;
    std::cin>>n;
    std::set<std::pair<std::string,std::string>>seen;
    bool duplicate=false;
    while(n--) {
        std::string first,last;
        std::cin>>first>>last;
        if(!seen.insert({first,last}).second)duplicate=true;
    }
    std::cout<<(duplicate?"Yes":"No")<<'\n';
}

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    solve();
}