7.15

#include<iostream>
#include<math.h>
using namespace std;
int main(){
    int a=0;
    cin>>a;
    cout<<"2^"<<a<<" = "<<pow(2.0,a)<<endl;
    return 0;
}

#include<iostream>
using namespace std;
double x(int a){
    double b=1;
    for(int i=1;i<=a;i++){
        b*=i;
    }
    return b;
}
int main(){
    double S=0;
    int N=0;
    if(N>10||N<0){
        return 0;
    }
    cin>>N;
    double A=1;
    for(int j=1;j<=N;j++){
        A=x(j);
        S+=A;
    }
    cout<<(int)S<<endl;
    return 0;
}

#include<iostream>
using namespace std;
int main(){
    cout<<"This is a simple problem."<<endl;
    return 0;
}

#include<iostream>
using namespace std;
int main(){
    int N;//正方形的边长
    char c;//输出的字符
    cin>>N;
    cin>>c;
    int n;
    //用于实现四舍五入
    if(N%2==0){
        n=N/2;
    }
    else{
        n=(N+1)/2;
    }
    for(int i=0;i<n;i++){
        for(int j=0;j<N;j++){
            cout<<c;
        }
        cout<<endl;
    }
    return 0;
}