Quite a Problem Solution:

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

int main(){
    // #ifndef TESTING
    // freopen("input.txt", "r", stdin);
    // freopen("output.txt", "w", stdout);
    // #endif

    string target("problem");
    string line;
    while(getline(std::cin, line)){
        transform(line.begin(), line.end(), line.begin(), ::tolower);
        size_t findResult = line.find(target);
        if(findResult == string::npos){
            cout << "no" << endl;
        } else {
            cout << "yes" << endl;
        }
    }

    return 0;
}