#include <cstdio>

template<class T>
T abs(T val) {
    return val >= 0 ? val : -val;
}

int invert(int n) {
    int x = -abs(2*n);
    const int incr = n > 0 ? -1 : 1;
    while (x++ < 0) {
        n += incr;
    }   
    return n;
}


void test(int n) {
    printf("%d inverted is %d\n", n, invert(n));
}

int main(int argc, char** argv) {
    test(1);
    test(22);
    test(-22);
    test(55);
    test(0);
    return 0;
}

1 inverted is -1
22 inverted is -22
-22 inverted is 22
55 inverted is -55
0 inverted is 0