text.cpp

// NOTE: it is recommended to use this even if you don't understand the following code.

#include <iostream>
#include <fstream>
#include <string>

using namespace std;

int main() {
//  uncomment the following lines if you want to read/write from files
//  ifstream cin("input.txt");
//  ofstream cout("output.txt");

	// input data
	int N, K;
    cin >> N >> K;
    
    string W[N];
    for(int i=0; i<N; i++)
        cin >> W[i];
	
    // insert your code here
    int l=0;
    for (int i=0; i<N; i++) {
    	if (l == 0) {
    		cout << W[i];
    		l += W[i].size();
		} else {
			if (l +1 + W[i].size() <= K) {
				cout << " " << W[i];
				l += W[i].size() +1;
			} else {
				cout << endl;
				l = 0;
				i--;
			}
		}
	}
    
    return 0;
}