题目

代码

#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
LL ex_gcd(LL a, LL b, LL &x, LL &y)
{
    if (b == 0)
    {
        x = 1;
        y = 0;
        return a;
    }

    LL gcd = ex_gcd(b, a % b, x, y);
    LL tmp = x;
    x = y;
    y = tmp - a / b * y;

    return gcd;
}
int main()
{
    LL x, y, m, n, l;
    cin >> x >> y >> m >> n >> l;

    LL a = n - m, b = l, c = x - y;
    LL X, Y;
    LL gcd = ex_gcd(a, b, X, Y);
    if (c % gcd)
    {
        cout << "Impossible";
        return 0;
    }

    X = X * c / gcd;
    b /= gcd;
    if (b < 0)
        b = -b;
    X = (X % b + b) % b;
    cout << X;
    return 0;
}