求大佬查错

#include "cstdio"
#include "cmath"
using namespace std;
int a[35],b[35],n,v,ans=1e9,x,y;
void dfs (int i){
	if (i>n){
		if (abs(x-y)<ans&&x+y>=v) ans=abs(x-y);
		return;
	}
	x+=a[i];y+=b[i];
	dfs(i+1);
	x-=a[i];y-=b[i];
	dfs(i+1);
}

int main (){
	scanf ("%d%d",&n,&v);
	for (int i=1;i<=n;i++) scanf ("%d%d",&a[i],&b[i]);
	dfs(1);
	if (ans==1e9){
		printf ("-1");
		return 0;
	}
	printf ("%d",ans);
	return 0;
}