#include<signal.h>
#include<unistd.h>
#include<errno.h>

volatile static sig_atomic_t n = 0;
const char msg[] = "Try again, please.\n";

void handle(){
        int save_errno = errno;
        signal(SIGINT, handle);
        n++;
        write(1, msg, sizeof(msg)-1);
        errno = save_errno;
}
int main(){
        signal(SIGINT, handle);
        while(n < 25)
                sleep(1);
        return 0;
}

~
~
~
~