#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
// using mint = modint1000000007;
// const int mod = 1000000007;
using mint = modint998244353;
const int mod = 998244353;
const int INF = 1e9;
const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i, l, r) for (int i = (l); i < (r); ++i)
#define rrep(i, n) for (int i = (n)-1; i >= 0; --i)
#define rrep2(i, l, r) for (int i = (r)-1; i >= (l); --i)
#define all(x) (x).begin(), (x).end()
#define allR(x) (x).rbegin(), (x).rend()
#define P pair<int, int>
template<typename A, typename B> inline bool chmax(A& a, const B& b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A& a, const B& b) { if (a > b) { a = b; return true; } return false; }

int main() {
	int n,a,b;cin>>n>>a>>b;
int ans=0;
rep2(i,1,n+1)if(i%a >i%b)ans++;
cout<<ans<<endl;
	return 0;
}