http://acm.zju.edu.cn/show_problem.php?pid=2705

#include "stdio.h"
#include "stdlib.h"
#include "math.h"
int Exec(int num,int extra)
{
int end=num/2;
int part1,part2;
int temp,count;
int maxcount=0;
for(int i=ceil(num/3);i<=end;i++)
{
part1=i;
part2=num-part1;
count=0;
while(part1!=part2)
{
if(2*part1 <part2)
{
count=0;
break;
}
else
{
count+=part1;
part2=part2-part1;

temp=part2;
part2=part1;
part1=temp;
}
}
if(part1==part2) count+=part1;
maxcount=(maxcount>count?maxcount:count);
}
return maxcount*extra;
}

int main()
{
int m,n;
int num1,num2;
while(scanf("%d%d",&m,&n)!=EOF)
{
num1=Exec(m,n);
num2=Exec(n,m);
printf("%d\n",num1>num2?num1:num2);
}
return 0;
}
---------------------------------------------------------------

int f0,f1,f2;
int max=(m>n)?m:n;
f0=1,f1=1;
do{
   f2=f1+f0;
   f0=f1;f1=f2;
}while(f2<max);
while(m%f2!=0&&n%f2!=0){
   f2=f1;f1=f0;
   f0=f2-f1;
}
printf("%lld",(long long)m*n-(long long)m*n/f2);