#include <bits/stdc++.h>   using namespace std;   long long x, y, m, cnt = 0;   int main() {     scanf( %lld%lld%lld , &x, &y, &m);     if (x >= m || y >= m) {       printf( 0 );       return 0;     }     if (x <= 0 && y <= 0) {       printf( -1 );       return 0;     }     while (x < m && y < m) {       if (x > y) swap(x, y);       if (x + y <= 0) {         cnt += abs(x) / y;         x = x + (abs(x) - abs(x) % y);       } else {         x += y;         cnt++;         ;       }     }     printf( %lld , cnt);     return 0;   }   