题解 | 墙壁划线

#include<bits/stdc++.h>
using namespace std;

int a,b,x,y;

int gcd(int m,int n){
	if(n==0) return m;
	else return gcd(n,m%n);
}

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	
	cin>>a>>b>>x>>y;
	
	int res=2*(a+b+1-gcd(a,b));
	if(a%2==0||b%2==0) res--;
	cout<<res<<endl;
	
    return 0;
}