Programación Competitiva

#include <bits/stdc++.h>
using namespace std;

int main() {
    int D, R, T;
    while (scanf("%d %d %d", &D, &R, &T) == 3) {
        int x = 0, y = 0;
        int a = 0, b = 0;
        while (true) {
            x++;
            if (x >= 4)
                a += x;
            if (x-y > D) {
                y++;
                if (y >= 3)
                    b += y;
            }
            if (a + b == R + T)
                break;
        }
        printf("%d\n", R-a);
    }
    return 0;
}