字符串最大跨距

#include<bits/stdc++.h>
using namespace std;
int main()
{
	string s,s1,s2;
	int i=0;
	char a;
	while(cin>>a)
		if(a!=',')
		{
			if(i==0)	s+=a;
			else if(i==1)	s1+=a;
			else	s2+=a;
		}
		else	i++;
	int t1,t2;
	t1=s.find(s1);	t2=s.rfind(s2);
	if(t1!=-1&&t2!=-1&&(t1+s1.length()-1)<t2)
		cout<<t2-t1-s1.length()<<endl;
	else	cout<<"-1"<<endl;
}