#include <iostream>
#include <stdio.h>
#include <string>

std::string exec(const char* cmd, const std::string &input) {
    FILE *input_pipe = popen(cmd, "w");
    FILE *output_pipe = popen(cmd, "r");

    if (!output_pipe || !input_pipe) {
        throw std::ios_base::failure("invalid command");
    }

    fputs(input.c_str(), input_pipe);
    pclose(input_pipe);

    char buffer[128];
    std::string result = "";
    while (!feof(output_pipe)) {
        if (fgets(buffer, 128, output_pipe) != NULL) {
            result += buffer;
        }
    }

    pclose(output_pipe);
    return result;
}

int main() {
    const char *cmd = "./other";
    std::cout << "output is \n" << exec(cmd, "3\n2 4 5");
}