merry.cpp

#include <iostream>
#include <cstdlib>
#include <ctime>

using namespace std;


int main(){
    srand((unsigned)time(NULL));
    char str[1024];
    while (cin.getline(str, sizeof(str))){
	int i = 0;
	while (i < 1024){
	    if (str[i] == '\0') break;
	    if (str[i] == ' ' && !(rand() % 10))
		str[i] = '　';
	    i++;
	}

	cout << str << endl;

    }
    return 0;
}