ABC151B - Achieve the Goal
#include <iostream> using namespace std; #define REP(i, n) for (int i = 0; i < (n); ++i) int main(void) { int n, k, m, a, sum = 0; cin.tie(0); ios::sync_with_stdio(false); cin >> n >> k >> m; REP(i, n - 1) { cin >> a; sum += a; } int ans = m * n - sum; if (k < ans) { ans = -1; } else if (ans < 0) { ans = 0; } cout << ans << "\n"; return 0; }