Cod sursa(job #645774)

Utilizator roots4Irimia Alexandru Gabriel roots4 Data 10 decembrie 2011 14:58:38
Problema Factorial Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.44 kb
#include <stdio.h>
long long st , dr , p , m ,a;
long long zero(long long x){
	long long k=5 , nr=0;
	for(k=5;k<=x;k*=5){
		nr+=x/k;
	}
	return nr;
}
int main(){
	freopen("fact.in","r",stdin);
	freopen("fact.out","w",stdout);
	scanf("%lld",&p);
	st=1;dr=5*p;
	while(st<=dr){
		m=(st+dr)/2;
		a=zero(m);		
		if(a<p)
			st=m+1;
		else
			dr=m-1;		
	}	
	if(zero(st)!=p)
		printf("%d",-1);
	else
		printf("%lld",st);
	return 0;
}