poj2661 Factstone Benchmark 数学

题目链接：http://poj.org/problem?id=2661

吴永辉《算法设计编程实验》1.1.1

///2014.4.12
///poj2661

#include <iostream>
#include <cstdio>
#include <string>
#include <cmath>
using namespace std;

int main()
{
    // freopen("in","r",stdin);
    // freopen("out","w",stdout);

    int a;
    while( cin>>a && a ){
        int k = 4;
        for(int i=1960 ; i/10<a/10 ; i+=10)
            k *= 2;
        int n=1;
        double sum = 0;
        for(n=1 ; sum<k ; n++){
            sum += log( (double)n )/log( (double)2 );
        }
        n -= 2;
        cout<<n<<endl;
    }
    return 0;
}