# include & ltcstdio & gt
int main()
{
long int X= 10，Y = 90
for(int k = 1； k & lt= 120; K++)// One unit for half a minute.
{
if(k % 2 = = 1)Y-= X； //Because X will eat Y half a minute after birth, and then Y will not be eaten within 1 minute, Y will always be eaten within odd half a minute, and because X will not grow at this time (the topic is to reduce the complexity of discussion), the number of X can be directly reduced.
if(k % 4 = = 0)Y * = 2； //Double every 2 minutes
if(k % 6 = = 0)X * = 2； //Double every 3 minutes. The doubling of x and y is independent of each other and need not be discussed separately.
}
printf("%d "，Y)；
Returns 0;
}