# Poj Solution 2815

```http://poj.org/problem?id=2815

#include <stdio.h>
#include <memory.h>
#include <string.h>
#include <math.h>

double get_angle( double s, double f, double m ) {

if( s >= 12 )
s -= 12;
s = ( s+f/60+m/7200 ) / 12 * 360;
f = ( f+m/120 )/60 * 360;
f -= s;
if( f < 0 )
f += 360;
return f;
}
double ans;
int main( ) {
int i, j, k, a, ii, jj, kk;
double t;
for( i=0; i<24; i++ )
for( j=0; j<60; j++ )
for( k=0; k<120; k++ )
ans[i][j][k] = get_angle( i, j, k );
//    printf( "%lf %lf %lfn", ans[21*2], ans[21*2+1], ans[22*2] );
while( 1 ) {
scanf( "%d %d:%d:%d", &a, &i, &j, &k );
t = ans[i][j][k*2];
if( a < 0 )
break;
if( fabs( t - a ) < 1e-7 ) {
printf( "%02d:%02d:%02dn", i, j, k );
continue;
}
ii = i, jj = j, kk = k;
for(  ; ; i=(i+1)%24 )
for( j%=60; j<60; j++ )
for( k%=60; k<60; k++ )
if( k != kk )
{
if( ans[i][j][2*k] - t > 0 ) {
if(    ans[i][j][k*2]-a > 0 && 0 <= a-t )
goto over;
}
else if( a-t >= 0 || 0 < ans[i][j][2*k]-a )
goto over;
t = ans[i][j][2*k];
ii=i, jj=j, kk=k;
//            printf( "%lfn", t );
}
over:
printf( "%02d:%02d:%02dn", ii, jj, kk );
}
return 0;
}

```
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