RT，代码提交之后是33分，第二监测点和第三监测点都错了，代码如下，请大佬们帮忙看看

#include<iostream>
#include<string>
#include<cstdio>
using namespace std;
int main(){
    unsigned long long int n,T;
    string a="\0",stack="\0",c="\0";
    cin>>n;
    for(unsigned long long int t=0;t<n;t++){
        cin>>T;
        for(unsigned long long int r=0;r<T;r++){
            cin>>a;
            if(a=="push"){
                cin>>c;
                c+=stack;
                stack=c;
                c="\0";
            }
            if(a=="query"){
                if(stack.length()!=0){
                    printf("%c\n",stack[stack.length()-1]);
                }else{
                    printf("Anguei!\n");
                }
            }
            if(a=="pop"){
                if(stack.length()!=0){
                   c="\0";
                   for(unsigned long long int l=0;l<stack.length()-1;l++){
                   	c[t]=stack[t];
				   }
				   stack=c;
				   c="\0";
                }else{
                    printf("Empty\n");
                }
            }
            if(a=="size"){
                printf("%d\n",stack.length());
            }
        }
    }
}