#include <stdio.h>

int main(void)
{
    int A, B, C;
    int flg = 0;
    scanf("%d %d %d", &A, &B, &C);
    for(int N = 1; N <= 200000; N++)
    {
        if(N * A - B > C)
        {
            break;
        }
        if((N * A - B == C) || ((N * A - B <= 0) && (N * A == C)))
        {
            printf("%d\n", N);
            flg = 1;
        }
    }
    if(flg == 0)
    {
        printf("%d", -1);
    }
    return 0;
}