题解：

算出每一位数在相加

#include<bits/stdc++.h>
using namespace std;
int main(){
	int a;
	cin>>a;
	cout<<a/100+a/10%10+a%10;
	return 0;
}

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

int main(){
    int n;cin>>n;
    int a=n/100;
    int b=n/10%10;
    int c=n%10;
    cout<<a+b+c;
    


    return 0;
}

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

int main(){
    int n;cin>>n;
    int a=n/100;
    int b=n/10%10;
    int c=n%10;
    cout<<a+b+c;
    


    return 0;
}

#include<iostream>
using namespace std;

int main(){
	int n; cin>>n;
	int a = n/100;
	int b = n/10%10;
	int c = n%10;
	cout<<a+b+c;
    return 0;
}