#include<stdio.h>
 
int main()
{
    int a, b, sum_a, sum_b;
 
    // 探索範囲
    for(a = 2; a <= 1500; a++){
        sum_a = 0;
 
        // a の約数の合計を計算
        for(int i = 1; i < a; i++){
            if(a % i == 0)
                sum_a += i;
        }
 
        b = sum_a; // b は a の約数の合計
 
        // b の約数の合計を計算
        sum_b = 0;
        for(int j = 1; j < b; j++){
            if(b % j == 0)
                sum_b += j;
        }
 
        // 友愛数の条件を満たすか確認
        if(a < b && sum_b == a){ // a < b による重複排除
            printf("%d と %d は友愛数です。\n", a, b);
        }
    }
 
    return 0;
}
 

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