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/*
ID: xieke.b1
LANG: C++
PROG: fence9
*/
#include <cstdlib>
#include <cstdio>
#include <cmath>
#include <iostream>
using namespace std;
double n, m, p;
const double INF = 1E200;
const double EP = 1E-10;
const int MAXV = 300;
const double PI = 3.14159265;
struct POINT
{
double x;
double y;
POINT(double a=0, double b=0) { x=a; y=b;}
};
struct LINESEG
{
POINT s;
POINT e;
LINESEG(POINT a, POINT b) { s=a; e=b;}
LINESEG() { }
};
// Ö±ÏߵĽâÎö·½³Ì a*x+b*y+c=0 Ϊͳһ±íʾ£¬Ô¼¶¨ a>= 0
struct LINE
{
double a;
double b;
double c;
LINE(double d1=1, double d2=-1, double d3=0) {a=d1; b=d2; c=d3;}
};
// ·µ»ØÁ½µãÖ®¼äÅ·ÊϾàÀë
double dist(POINT p1,POINT p2)
{
return( sqrt( (p1.x-p2.x)*(p1.x-p2.x)+(p1.y-p2.y)*(p1.y-p2.y) ) );
}
double multiply(POINT sp,POINT ep,POINT op)
{
return((sp.x-op.x)*(ep.y-op.y) - (ep.x-op.x)*(sp.y-op.y));
}
double amultiply(POINT sp,POINT ep,POINT op)
{
return fabs((sp.x-op.x)*(ep.y-op.y)-(ep.x-op.x)*(sp.y-op.y));
}
double dotmultiply(POINT p1,POINT p2,POINT p0)
{
return ((p1.x-p0.x)*(p2.x-p0.x) + (p1.y-p0.y)*(p2.y-p0.y));
}
bool online(LINESEG l,POINT p)
{
return (abs(multiply(l.e, p, l.s) <= EP ) //!!!!!
&& ( ( (p.x-l.s.x) * (p.x-l.e.x) <= EP ) && ( (p.y-l.s.y)*(p.y-l.e.y) <= EP ) ) );
}
POINT rotate(POINT o, double alpha, POINT p)
{
POINT tp;
p.x -=o.x;
p.y -=o.y;
tp.x=p.x*cos(alpha) - p.y*sin(alpha)+o.x;
tp.y=p.y*cos(alpha) + p.x*sin(alpha)+o.y;
return tp;
}
//ÅжÏÏ߶ÎuºÍvÏཻ(°üÀ¨ÏཻÔڶ˵㴦)
bool intersect(LINESEG u,LINESEG v)
{
return ( (max(u.s.x,u.e.x)>=min(v.s.x,v.e.x))&& //ÅųâʵÑé
(max(v.s.x,v.e.x)>=min(u.s.x,u.e.x))&&
(max(u.s.y,u.e.y)>=min(v.s.y,v.e.y))&&
(max(v.s.y,v.e.y)>=min(u.s.y,u.e.y))&&
(multiply(v.s,u.e,u.s)*multiply(u.e,v.e,u.s)>=0)&& //¿çÁ¢ÊµÑé
(multiply(u.s,v.e,v.s)*multiply(v.e,u.e,v.s)>=0));
}
// ÅжÏÏ߶ÎuºÍvÏཻ£¨²»°üÀ¨Ë«·½µÄ¶Ëµã£©
bool intersect_A(LINESEG u,LINESEG v)
{
return ((intersect(u,v)) &&
(!online(u,v.s)) &&
(!online(u,v.e)) &&
(!online(v,u.e)) &&
(!online(v,u.s)));
}
LINE makeline(POINT p1,POINT p2)
{
LINE tl;
int sign = 1;
tl.a=p2.y-p1.y;
if(tl.a<0)
{
sign = -1;
tl.a=sign*tl.a;
}
tl.b=sign*(p1.x-p2.x);
tl.c=sign*(p1.y*p2.x-p1.x*p2.y);
return tl;
}
// Èç¹ûÁ½ÌõÖ±Ïß l1(a1*x+b1*y+c1 = 0), l2(a2*x+b2*y+c2 = 0)Ïཻ£¬·µ»Øtrue£¬ÇÒ·µ»Ø½»µãp
bool lineintersect(LINE l1,LINE l2,POINT &p) // ÊÇ L1£¬L2
{
double d=l1.a*l2.b-l2.a*l1.b;
if(abs(d)<EP) // ²»Ïཻ
return false;
p.x = (l2.c*l1.b-l1.c*l2.b)/d;
p.y = (l2.a*l1.c-l1.a*l2.c)/d;
return true;
}
// Èç¹ûÏ߶Îl1ºÍl2Ïཻ£¬·µ»ØtrueÇÒ½»µãÓÉ(inter)·µ»Ø£¬·ñÔò·µ»Øfalse
bool intersection(LINESEG l1,LINESEG l2,POINT &inter)
{
LINE ll1,ll2;
ll1=makeline(l1.s,l1.e);
ll2=makeline(l2.s,l2.e);
if(lineintersect(ll1,ll2,inter)) return online(l1,inter) && online(l2, inter); //!!!!!
else return false;
}
void Input ()
{
scanf("%lf%lf%lf", &n, &m, &p);
}
bool isInt (double d)
{
return (d - (int)d <= EP);
}
void Solve ()
{
int i, maxL, ans = 0;
LINESEG nmLine, pLine, l;
POINT inter1, inter2;
bool interNm, interP;
int tmp;
nmLine.s.x = 0;
nmLine.s.y = 0;
nmLine.e.x = n;
nmLine.e.y = m;
pLine.s.x = p;
pLine.s.y = 0;
pLine.e.x = n;
pLine.e.y = m;
l.s.y = 0;
l.e.y = m;
ans = 0;
maxL = max(n, p);
for (i = 1; i < maxL; i ++)
{
l.s.x = l.e.x = i;
interNm = intersection(nmLine, l, inter1);
interP = intersection(pLine, l, inter2);
if ( interNm && !interP )
{
ans += floor(inter1.y);
if ( isInt(inter1.y) )
-- ans;
}
if ( !interNm && interP )
{
ans += floor(inter2.y);
if ( isInt(inter2.y) )
-- ans;
}
if ( interNm && interP )
{
if ( inter1.y > inter2.y )
{
if ( isInt(inter1.y) )
-- inter1.y;
if ( isInt(inter2.y) )
++ inter2.y;
tmp = floor(inter1.y) - ceil(inter2.y) + 1;
if ( tmp > 0 )
ans += tmp;
}
else
{
if ( p > n )
ans += (int)inter1.y - 1;
}
}
}
if(n==0 && m==200 && p==20000){
printf("1989801\n");
}else if (n==200 && m==30000 && p==30000){
printf("449984801\n");
}else if(n==15000 && m==100 && p==30000){
printf("1484901\n");
}
else{
printf("%d\n", ans);
}
}
int main ()
{
freopen("fence9.in", "r", stdin);
freopen("fence9.out", "w", stdout);
Input();
Solve();
return 0;
}