#include <iostream>
using namespace std;
int vp,vd,t,f,c;
bool check(int num)
{
int i=t;
int j=0;
while(num >= 0 && i < c)
{
for (;j<i;i+=vp,j+=vd);
num--;
if (num < 0 && i < c )
{
return false ;
}
else if (num < 0 && i == c )
return true;
for (;j>0 ; i+=vp , j-=vd);
j=0;
for (int k=0;k<f;k++)
i+=vp;
}
}
int binary_sear()
{
int s=1;
int e=c/f;
int ret=0;
while (s<=e)
{
int mid=(s+e)/2;
if (check(mid))
{
e=mid-1;
ret=mid;
}
else
{
s=mid+1;
}
}
return ret;
}
int main()
{
cin >> vp >> vd >> t >> f >> c ;
if (vp > vd)
{
cout << 0 << endl;
return 0;
}
cout << binary_sear() << endl;
return 0;
}
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