17国庆day4

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 
 4 int main() {
 5     int d, r, t;
 6     scanf("%d %d %d", &d, &r, &t);
 7     for(int i = 4; i < 100; i++){
 8         int a = (i+4)*(i-3)/2;
 9         int b = (i+3-d)*(i-d-2)/2;
10         if(a+b == r+t) {
11             printf("%d\n", r-a);
12             return 0;
13         }
14     }
15 }