感觉没问题但是通过率只有10/12

#include<iostream>
#include<string>
using namespace std;

int main(){
    string Str;
    char Ctr;
    cin>>Str;
    cin>>Ctr;
    int count=0;
    int N=Str.size();
    if('A'<=Ctr<='Z'){
        for(int i=0;i<N;i++){
            if(Str[i]==Ctr || Str[i]==Ctr+32){
                count++;
            }
        }
        cout<<count<<endl;
    }
    else if('a'<=Ctr<='z'){
        for(int i=0;i<N;i++){
            if(Str[i]==Ctr || Str[i]==Ctr-32){
                count++;
            }
        }
        cout<<count<<endl;
    }
    else if('0'<=Ctr<='9'){
        for(int i=0;i<N;i++){
            if(Str[i]==Ctr){
                count++;
            }
        }
        cout<<count<<endl;
    }
    else{
        count=0;
    }
    return 0;
}