백준 1065 C++

#include <iostream>
#define max 1000
using namespace std;

void cal(int n){
    int a,b,c,cnt=0;
    for(int i=100; i<=n; i++){
        a = i/100; //백의자리수
        b = (i%100)/10; //십의자리수
        c = (i%100)%10; //일의자리수
        if((a-b) == (b-c)) cnt++;
    }
    cout << 99+cnt << endl;
}

int main(){
    int n;
    cin >> n;

    if(n < 100) cout << n << endl;
    if(n > 99){
        cal(n);
    }
    return 0;
}