39 lines
756 B
C++
39 lines
756 B
C++
#include <bits/stdc++.h>
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using namespace std;
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#define int long long
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#define endl "\n"
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int exgcd(int a, int b, int &x, int &y) {
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if (!b) {
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x = 1, y = 0;
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return a;
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}
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int d = exgcd(b, a % b, y, x);
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y -= a / b * x;
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return d;
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}
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int n, a1, m1, a2, m2, k1, k2;
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signed main() {
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cin >> n >> a1 >> m1;
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n--;
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while (n--) {
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cin >> a2 >> m2;
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int d = exgcd(a1, -a2, k1, k2);
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if ((m2 - m1) % d) {
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cout << -1 << endl;
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exit(0);
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}
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k1 *= (m2 - m1) / d;
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int t = abs(a2 / d);
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k1 = (k1 % t + t) % t;
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m1 = k1 * a1 + m1;
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a1 = abs(a1 / d * a2);
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}
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cout << (m1 % a1 + a1) % a1 << endl;
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} |