Language: C

/**
 * code generated by JHelper
 * More info: https://github.com/AlexeyDmitriev/JHelper
 * @author champon
 */

#include <iostream>
#include <fstream>

#include <bits/stdc++.h>
#define se cout << "test ok" << endl;
#define sp << " " <<
#define enl "\n";
using namespace std;
using ll=long long;
using ld=long double;
ll mod = ll(1e9)+7;
ll inf = ll(1e18);
void bl(bool b, ostream& out=cout){ out << (b ? "Yes" : "No") << endl; }
void bl2(bool b, ostream& out=cout){ out << (b ? "YES" : "NO") << endl; }
template<typename T> inline bool chmax(T &a, T b){ if(a<b){a=b; return true;} return false; }
template<typename T> inline bool chmin(T &a, T b){ if(a>b){a=b; return true;} return false; }
template<typename A, size_t N, typename T> void Fill(A (&array)[N], const T &val){ fill((T*)array, (T*)(array+N), val); }
int dx[] = {1, 0, -1, 0, 1, -1, 1, -1};
int dy[] = {0, 1, 0, -1, 1, -1, -1, 1};

#ifndef INCLUDE_DEBUG_HPP
#define INCLUDE_DEBUG_HPP

#include <iostream>
#include <vector>
#include <map>
using namespace std;

namespace dbg {
    using ll = long long;

    class Debug {
    public:
        Debug(){}
        template<typename T>
        void vd(vector<T> vec);
        template<typename T>
        void vd2(vector<vector<T>> vec);
        template<typename T>
        void ad(T *arr, ll n);
        template<typename T, size_t N>
        void ad2(T (&arr)[N], ll n);
        template<typename T>
        void md(T mp);
    };

    template<typename T>
    void Debug::vd(vector<T> vec) {
        for (auto vv : vec) cout << vv << " ";
        cout << endl;
    }

    template<typename T>
    void Debug::vd2(vector<vector<T>> vec) {
        for (auto vv : vec) for (auto vvv : vv) cout << vvv << " ";
        cout << endl;
    }

    template<typename T>
    void Debug::ad(T *arr, ll n) {
        for (int i = 0; i <= n; i++) cout << arr[i] << " ";
        cout << endl;
    }

    template<typename T, size_t N>
    void Debug::ad2(T (&arr)[N], ll n) {
        for (int i = 0; i <= N; i++) for (int j = 0; j <= n; j++) cout << arr[i][j] << " ";
        cout << endl;
    }

    template<typename T>
    void Debug::md(T mp) {
        cout << "key : value" << endl;
        for (auto const &m : mp) cout << m.first << " : " << m.second << endl;
        cout << endl;
    }

}

#endif //INCLUDE_DEBUG_HPP

using dbg::Debug;
Debug debug;

#ifndef DEFINE_MATH_HPP
#define DEFINE_MATH_HPP

namespace math {

    using ll = long long;
    ll mod = ll(1e9) + 7;

    class Math {
    public:
        Math() {}
        ll keta(ll num);
        ll gcd(ll a, ll b);
        ll lcm(ll a, ll b);
        ll powm(ll num1, ll num2);
    };

    ll Math::gcd(ll a, ll b) {
        if (b == 0) return a;
        return gcd(b, a % b);
    }

    ll Math::lcm(ll a, ll b) {
        return a * (b / gcd(a, b));
    }

    ll Math::keta(ll num) {
        ll k = 0;
        while (num > 0) {
            num /= 10;
            k++;
        }
        return k;
    }

    ll Math::powm(ll a, ll b) {
        ll res = 1;
        while (b > 0) {
            if (b & 1) (res *= a) %= mod;
            (a *= a) %= mod;
            b >>= 1;
        }
        return res;
    }

}

#endif //DEFINE_MATH_HPP

using math::Math;

class CSumOfGcdOfTuplesEasy {
public:
	void solve(std::istream& in, std::ostream& out) {
	    int k;
	    in >> k;

	    ll res = 0;
	    Math mt;
	    for(int a=1; a<=k; a++){
	        for(int b=1; b<=k; b++){
	            ll buf = mt.gcd(a, b);
	            for(int c=1; c<=k; c++){
                    res += mt.gcd(buf, c);
	            }
	        }
	    }

	    out << res << endl;
	}
};


int main() {
	CSumOfGcdOfTuplesEasy solver;
	std::istream& in(std::cin);
	std::ostream& out(std::cout);
	solver.solve(in, out);
	return 0;
}


Compiler output:
main.c:7:10: fatal error: iostream: No such file or directory
    7 | #include <iostream>
      |          ^~~~~~~~~~
compilation terminated.