对于每个字母分别hash。
数据生成器：
#include<bits/stdc++.h>
inline const void write(int a)
{
if(a>9)write(a/10);
putchar(a%10+'0');
}
int main()
{
freopen(".in","w",stdout);
srand(0);
int n=rand()%10000,m=rand()%1000;
write(n);putchar(' ');write(m);printf("\n");
for(int i=1;i<=n;i++)putchar('a'+rand()%26);
printf("\n");
for(int i=1;i<=n;i++)putchar('a'+rand()%26);
printf("\n");
while(m)
{
int q=rand()%400;
write(q);printf("\n");
while(q){q--;putchar('a'+rand()%26);putchar(' ');putchar('a'+rand()%26);putchar(' ');}
printf("\n");
m--;
}
return 0;
}