40 lines
713 B
C++
40 lines
713 B
C++
#include<cstdio>
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#include<cstring>
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#include<cmath>
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#include<iostream>
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#include<algorithm>
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using namespace std;
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int main()
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{
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int t;
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cin>>t;
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while(t--)
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{
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long long n,m,v,k;
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cin>>n>>m>>v>>k;
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if(m>=n)
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{
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cout<<0<<endl;
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}
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else
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{
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int co=0;
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while(m<n)
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{
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if((m-v)*k>m)
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{
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m=(m-v)*k;
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co++;
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}
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else
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{
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co=-1;
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break;
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}
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}
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cout<<co<<endl;
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}
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}
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return 0;
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}
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