历届试题 买不到的数目

#include<iostream>
#include<string>
#include<cstring>
#include<cstdio>
#include<cstdlib>
using namespace std;
int n,m;
int GCD(int n,int m)
{
    if(n<m)
    {
        int t;
        t = n;
        n = m;
        m = t;
    }
    return n%m==0?m:GCD(m,n%m);
}
int solve(int n,int m)
{
    int i,j,k,t,flag,ans;
    int gcd = (n* m) / GCD(n,m); 
    if(n<m)
    {
        t = n;
        n = m;
        m = t;
    }
    int x = (gcd / m) + 1;
    for(i=gcd;i>=1;i--)
    {
        flag = 0;
        for(k=0;k<=x;k++)
        {
            for(j=x;j>=0;j--)
            {
                if((k != 0 ||j != 0) && i % (n*k + m*j) == 0)
                    flag = 1;
            }
        }
        if(flag==0)
        {
            ans = i;
            break;
        }
    }
    return ans ;
}
int main()
{
    while(cin>>n>>m)
    {
        int d ;d =solve(n,m);
        cout<<d<<endl;
    }
    return 0;
}