My prime generator code in classical problem always shows error even if my code is correct. I’m using c++(gc 4.5.3)

#include
#include
#include
#include

bool checkPrime(long long N) {
long long sqrtN = sqrt(N);
if(N < 2) return false;
for(long long i = 2; i <= sqrtN; i++) {
if(N%i == 0)
return false;
}
return true;
}

int main() {
long long T;
std::cin >> T;
while(T–) {
long long start, end;
std::cin >> start >> end;
for(long long i = start; i <= end; i++) {
if(checkPrime(i) == true)
std::cout << i << std::endl;
}
std::cout << std::endl;
}
}