var
FD: text;
y, step, first, last: real;
begin
write('Введите начальное значение, конечное значение и шаг:');
read(first, last, step);
assign(FD, 'tabl.txt');
rewrite(FD);
writeln(FD, 'x':4, 'f(x)':10);
while (first <= last) do
begin
if (first.Between(0.41, 0.58)) then
writeln(FD, first:4:2, 'infinity':10)
else
begin
y := (2 * first + 1) / (2 * first - 1);
writeln(FD, first:4:2, y:10:4);
end;
first := first + step;
end;
close(FD);
end.
#include <iostream>
typedef long long ll;
using namespace std;
bool ll_is_valid(ll t, ll N, ll x, ll y)
{
return t / x + (t - x) / y >= N;
}
ll f(ll N, ll x, ll y)
{
ll R = 1;
while (!ll_is_valid(R,N,x,y)) R *= 2;
ll L = R / 2;
while(R - L > 1)
{
ll M = (L + R) / 2;
if (!ll_is_valid(M,N,x,y)) {L = M;}
else {R = M;}
}
return R;
}
int main()
{
ll N,x,y;
cin >> N >> x >> y;
if(x > y) swap( x, y );
cout << f(N, x, y) << std::endl;
}