Cod sursa(job #1944238)
Utilizator | Daniel Marcu marcudanf | Data | 29 martie 2017 00:33:59 |
---|---|---|---|
Problema | Factorial | Scor | 5 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.75 kb |
#include <fstream>
using namespace std;
ifstream fin("fact.in");
ofstream fout("fact.out");
int p;
int check(int x){
int p=5,s=0;
while(x/p){
s+=x/p;
p*=5;
}
return p;
}
int caut(){
int l=1,r=500000000,sol=-1,mid;
while(l<=r){
mid=(l+r)/2;
int a=check(mid);
if(a>p){
r=mid-1;
}else if(a<p){
l=mid+1;
}else{
l=mid+1;
sol=mid;
return sol;
}
}
return sol;
}
int main()
{
fin>>p;
if(p==0)
fout<<1;
else{
int a=caut();
if(a){
fout<<a-a%5;
}else{
fout<<-1;
}
}
return 0;
}