#include<iostream> #include<cstring> using namespace std; int main() { char a; double s; double n; n = 0; char b[201]; cin >> a; gets (b); strlwr (b); for(int i = 0;i < strlen(b);i++) { if(a == b[i]) { n++; } } s = n / (strlen(b) - 1); printf("%.5lf",s); return 0; }