代码

#include <iostream>
#include <string>
#include <algorithm>

using namespace std;

int main()
{
    string s, s1, s2;
    char a;
    int m = 0;
    while(cin >> a)
    {
        if(a != ',')
        {
            if(m == 0) s += a;
            if(m == 1) s1 += a;
            if(m == 2) s2 += a;
        }
        else if(a == ',') m ++;
    }
    int i, j, k;
    i = s.find(s1);
    j = s.rfind(s2);
    if(s.find(s1) == string::npos || s.find(s2) == string::npos || i + s1.size() >= j) cout << -1;
    else
    {
        k = j - i - s1.size();
        cout << k;
    }

    return 0;
}