杭电2131

#include <iostream>#include <cstdio>#include <cstring>using namespace std;int main(){char ch[2];char s1[210];int len,i,j,sum;while(~scanf("%s%s",ch,s1)){sum=0;len=strlen(s1);if(ch[0]>='A'&&ch[0]<='Z'){for(i=0;i<len;i++){if(s1[i]>='a'&&s1[i]<='z')s1[i]-=32;}}else{for(i=0;i<len;i++){if(s1[i]>='A'&&s1[i]<='Z')s1[i]+=32;}}for(i=0;i<len;i++){if(s1[i]==ch[0]){sum++;}}printf("%.5lf\n",1.0*sum/len); }return 0;}