#include <bits/stdc++.h>
using namespace std;
main(){
int n,a,b,i,s,max;
max = 2000000000;
cin >> n >> a >> b;
i = 1;
while (i * b <= n){
s = ((n - (i * b)) / a) + i;
if ((s - i) * a + i * b == n && max > s) {
max = s;
}
i++;
}
if (max == 2000000000 ){
cout << "-1";
} else{
cout << max;
}
}
