Now I have:
Input: 10 10 Answer: 10
Input: 13 14.1 Answer: 15

but:
float p, q;
scanf ("%f %f", &p, &q);
p/=100;
q/=100;

result: WA6

but:
float p, q;
scanf ("%f %f", &p, &q);
p=(float)((int)(p*100))/10000.00;
q=(float)((int)(q*100))/10000.00;
//Only 2 digits after dot

result: WA3

Why?

PS (ceil(p*cnt)-((int)(q*cnt)))>1e-7

Use double,don't float