#include <iostream>

// This program queries the user for a non-negative
// integer 'n' and then calculates the integer square
// root of that value.
//
// The integer square root of 'n' is the largest
// non-negative integer 'isqrt' such that
//
//     isqrt*isqrt <= n.
//
// For example, the integer square root of 20 is 4,
// because
//
//     4*4 <= 20
//
// but
//
//     5*5 > 20.
//
// If n < 0, simply return 0.
//
// Exercise:
//
//   Eliminate the loop variable 'm'. Can you use
//   'isqrt' itself as the loop variable?

// Function declarations
int main();

// Function definitions
int main() {
    int n{};

    std::cout << "Enter a non-negative integer: ";
    std::cin  >> n;

    if ( n < 0 ) {
        return 0;
    }

    int isqrt{};

    for ( int m{ 0 }; true; ++m ) {
        if ( m*m <= n ) {
            isqrt = m;
        } else {
            break;
        }
    }

    std::cout << "The integer square root of "
              << n << " is " << isqrt << "."
              << std::endl;

    std::cout << isqrt << "*" << isqrt
              << " = " << isqrt*isqrt
              << " <= " << n << " < "
              << (isqrt + 1) << "*" << (isqrt + 1)
              << " = " << (isqrt + 1)*(isqrt + 1)
              << std::endl;

    return 0;
}



























// Hint:
//
// The variable 'm' starts at 0 and increases until
// its square is greater than 'n'.
//
// At the end of each successful iteration, its value
// is copied into 'isqrt'.
//
// Could 'isqrt' itself start at 0 and increase until
// its square becomes greater than 'n'?
//
// If so, what must you do after the loop terminates?



























// Here is one solution:
/*
int main() {
    int n{};

    std::cout << "Enter a non-negative integer: ";
    std::cin  >> n;

    if ( n < 0 ) {
        return 0;
    }

    int isqrt{};

    for ( ; isqrt*isqrt <= n; ++isqrt ) {
        // Do nothing.
    }

    --isqrt;

    std::cout << "The integer square root of "
              << n << " is " << isqrt << "."
              << std::endl;

    std::cout << isqrt << "*" << isqrt
              << " = " << isqrt*isqrt
              << " <= " << n << " < "
              << (isqrt + 1) << "*" << (isqrt + 1)
              << " = " << (isqrt + 1)*(isqrt + 1)
              << std::endl;

    return 0;
}
*/