Kyselyt

#include <iostream>
#include <math.h>

int c(std::string x) {
	std::string::size_type sz;
	int a = (int)pow(10.0, (double)x.length() - 1.0);
	int b = std::stoi(x,&sz);
	if (b < 10) return b;
	if (b == a) { return 1; }
	if (b == (a + 1)) { return 0; }
	return b - (b/a);
}

int main() {
	int s;
	std::string out = "";
	std::string y;
	
	std::cin >> s;
	
	for (int i = 0; i < s; ++i) {
		std::cin >> y;
		int n = c(y);
		out.append(std::to_string(n));
		out.append("\n");
	}
	
	std::cout << out;
}

Test 1

Group: 1

Verdict: WRONG ANSWER

Test 2

Group: 2

Verdict: WRONG ANSWER

Test 3

Group: 3

Verdict: RUNTIME ERROR

terminate called after throwing an instance of 'std::out_of_range'
  what():  stoi