# 题目

{% fold 点击显/隐题目 %}

0 1 1 2 6
5
{% endfold %}

# 代码

{% fold 点击显/隐代码 %}```cpp 扩展欧几里得 https://github.com/OhYee/sourcecode/tree/master/ACM 代码备份
#include
#include
using namespace std;

// gcd(a,b)
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }

// ax + by = gcd(a,b)
long long ex_gcd(long long a, long long b, long long &x, long long &y) {
if (!b) {
x = 1;
y = 0;
return a;
} else {
long long d = ex_gcd(b, a % b, y, x);
y -= x * (a / b);
return d;
}
}

// ax + by = c
bool solve(long long a, long long &x, long long b, long long &y, long long c,
long long minx) {
long long d = ex_gcd(a, b, x, y);
if (c % d)
return false;

``````long long m = b / d;
if (m < 0)
m = -m;
x *= c / d;
x = (x % m + m) % m;
y = (c - a * x) / b;
return true;
``````

}

int main() {
cin.tie(0);
cin.sync_with_stdio(false);
long long s1, s2, v1, v2, m;
while (cin >> s1 >> s2 >> v1 >> v2 >> m) {
long long x, y;
if (solve(v1 - v2, x, m, y, s2 - s1, 0))
cout << x << endl;
else
cout << "-1" << endl;
}
return 0;
}

`{% endfold %}`