zoj 1707 Automatic Editing

#include<iostream>using namespace std;int main(){    int n;    while(cin >> n && n != 0)    {        string from[16],to[16];        getline(cin,from[0]);        for(int i = 0; i < n; ++i)        { getline(cin,from[i]); getline(cin,to[i]);        }        string str;        getline(cin,str);        for(int i = 0; i < n; ++i)        { int pos; while((pos = str.find(from[i])) != string::npos)     str.replace(pos,from[i].size(),to[i]);        }        cout << str << endl;    }    return 0;}