暴力#

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#include<bits/stdc++.h>
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#define int long long
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using namespace std;
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int n;
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void Merge(int &b1, int &a1, int b2, int a2)
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{
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  if(a1 < a2) swap(b1, b2), swap(a1, a2);
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  while(b1 % a2 != b2)
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  {
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    b1 += a1;
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  }
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  a1 = a1 / __gcd(a1, a2) * a2;
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}
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//a为模数，b为余数
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signed main()
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{
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  ios::sync_with_stdio(0), cin.tie(0);
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  int bstar = 0, astar = 1;
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  int b, a;
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  cin >> n;
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  for(int i = 1;i <= n;i++)
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  {
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    cin >> a >> b;
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    b%= a;
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    Merge(bstar, astar, b, a);
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  }
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  printf("%lld", bstar);
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  return 0;
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}