UVA_10114_Loansome_Car_Buyer

#include <stdio.h>

int main() {
  int M, N;
  double first, cost;
  while (scanf("%d%lf%lf%d", &M, &first, &cost, &N) && M >= 0) {
    double deps[999] = {};
    while (N--) {
      int startM;
      scanf("%d", &startM);
      scanf("%lf", &deps[startM]);
    }
    double value = first + cost, owes = cost, earn = cost / M;
    int i;
    for (i = 0; i <= M; i++) {
      if (!deps[i]) {
        deps[i] = deps[i - 1];
      }
      value = value * (1 - deps[i]);
      if (value >= owes) {
        printf("%d %s%s\n", i, "month", i != 1 ? "s" : "");
        break;
      }
      owes -= earn;
    }
  }
  return 0;
}