#define _USE_MATH_DEFINES
#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <complex>
#include <string>
#include <vector>
#include <array>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
#include <iterator>
#include <memory>
#include <regex>
using namespace std;

long long gcd(long long a, long long b){
    while(b != 0){
        long long tmp = a % b;
        a = b;
        b = tmp;
    }
    return a;
}

long long lcm(long long a, long long b){
    long long g = gcd(a, b);
    if(a / g <= LLONG_MAX / b)
        return a / g * b;
    else
        return LLONG_MAX;
}

int main()
{
    long long t, a, b;
    cin >> t >> a >> b;
    -- t;

    long long c = lcm(a, b);
    long long ans = t / a + t / b - t / c + 1;
    cout << ans << endl;

    return 0;
}