【CodeForces】[448D]Multiplication Table

#include<stdio.h>
#include<algorithm>
using namespace std;
__int64 n,m,k;
bool find(__int64 x) {
__int64 cnt=0;
for(int i=1; i<=n; i++) {
cnt+=min(m,x/i);
}
return cnt>=k;
}
int main() {
while(scanf("%I64d %I64d %I64d",&n,&m,&k)!=EOF) {
__int64 l=1,r=n*m,res;
while(l<=r) {
__int64 mid=(r+l)/2;
if(find(mid)) {
res=mid;
r=mid-1;
} else
l=mid+1;
}
printf("%I64d\n",res);
}
return 0;
}