#include <iostream>
using namespace std;
#define START 1901
#define END 2000
bool
isLeap(int y)
{
if (y%4 != 0 || (y%100 == 0 && y%400 != 0))
{
return false;
}
else
{
return true;
}
}
int
main(int argc, char **argv)
{
int md[13] = { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
int w = 1 + 365;
int ans = 0;
for (int y = START; y <= END; y++)
{
if (isLeap(y))
{
md[2] = 29;
}
else
{
md[2] = 28;
}
for (int m = 1; m <= 12; m++)
{
if (w%7 == 0)
{
ans++;
}
w += md[m];
}
}
cout << ans << endl;
return 0;
}